feat(cc-config): manage plugins, marketplaces, hooks and settings from the dashboard

The Claude Config page was read-only for these four surfaces. It can now:

- register a marketplace from a pasted GitHub `owner/repo`, http(s) URL or
  absolute path, and install / enable / disable / update / uninstall plugins,
  all delegated to the `claude plugin …` CLI so its registry stays consistent;
- edit hooks and settings.json keys in the user, project and project-local
  layers.

Server:

- `server/lib/cc-plugin-cli.js` wraps the CLI with `execFile` and an explicit
  argv array — never a shell string. Every argument is validated before the
  spawn (shape allowlist per kind, no control characters, no leading `-`, no
  `..`), `CLAUDE_CONFIG_DIR` is pinned to the dashboard's CLAUDE_HOME, stdin is
  closed so a prompt errors instead of hanging, and mutating calls are
  serialized in-process.
- `cc-mutate.patchSettings` merges individual dotted keys into one settings
  layer. It re-reads the file unredacted, so keys the UI never displayed —
  including secret-valued ones — survive byte-for-byte. A payload carrying the
  `<redacted>` placeholder is refused (EREDACTED), as are `__proto__` /
  `prototype` / `constructor` segments; a settings file that does not parse is
  reported (EBADJSON) rather than clobbered. Backup first, then atomic write.
- Six additive routes on /api/cc-config; a non-zero CLI exit is a 422 carrying
  the CLI's own message, a missing binary a 503.

Client: install/add bars, per-card plugin and marketplace actions behind a
two-click confirm, and edit modes for hooks and settings that send only the
keys that changed. New i18n keys in en + vi; the explainer banners that said
these surfaces were read-only now describe what the writes actually do.

Tests: 61 new server tests (CLI argv construction and validation, the settings
key-merge, and the six routes against a fake `claude` on PATH).

docs/API.md

@@ -1441,7 +1441,7 @@ curl "http://localhost:4820/api/sessions?sources=local,4d1f0e2a-7b9c-4c33-8a21-9
 
 ### Claude Config Explorer
 
-The `/api/cc-config/*` namespace powers the Claude Config Explorer page. All read endpoints are pure file reads under `CLAUDE_HOME` and the project's `.claude/` dir; mutations are limited to low-risk text-file artifacts (skills, subagents, slash commands, output styles, memory) and always create a timestamped backup before writing. Plugins, MCP servers, hooks-in-settings, and live `settings.json` files stay read-only because they are written concurrently by the running Claude Code CLI.
+The `/api/cc-config/*` namespace powers the Claude Config Explorer page. All read endpoints are pure file reads under `CLAUDE_HOME` and the project's `.claude/` dir. File mutations cover the low-risk text-file artifacts (skills, subagents, slash commands, output styles, memory), `keybindings.json`, and `settings.json` layers **via a per-key merge only** — each always creates a timestamped backup before writing. Plugin and marketplace management is delegated to the `claude plugin …` CLI. MCP server config stays read-only, because it is written concurrently by the running Claude Code CLI.
 
 ```http
 GET /api/cc-config/overview
@@ -1463,13 +1463,23 @@ GET /api/cc-config/file?path=<absolute-path>
 GET /api/cc-config/backups[?scope=&type=]
 PUT /api/cc-config/file        Body: { scope, type, name?, content }
 DELETE /api/cc-config/file     Body: { scope, type, name? }
+PATCH /api/cc-config/settings  Body: { scope, set?: { "dotted.key": value }, unset?: ["dotted.key"] }
+GET /api/cc-config/plugins/available
+POST /api/cc-config/plugins/install       Body: { spec, scope? }
+POST /api/cc-config/plugins/action        Body: { key, action: enable|disable|update|uninstall }
+POST /api/cc-config/marketplaces/add      Body: { source, scope? }
+POST /api/cc-config/marketplaces/action   Body: { name, action: update|remove }
 ```
 
 `scope` is `"user"`, `"project"`, or `"auto-memory"`. `type` is one of `skills`, `agents`, `commands`, `output-styles`, `memory`, `auto-memory`. `name` is required for everything except `memory` (which is `CLAUDE.md` itself). On `PUT`, `name` is validated against `^[A-Za-z0-9][A-Za-z0-9._-]{0,63}$` (for `auto-memory` it must instead be a flat `*.md` filename). Settings are returned with secret-like keys (matching `/token|secret|password|api[_-]?key|auth/i`) replaced by `"<redacted>"`.
 
 `GET /api/cc-config/memory` also surfaces the per-project file-based memory store — every `*.md` under `~/.claude/projects/<slug>/memory/` (the common pattern of a `MEMORY.md` index plus one file per remembered fact). Those items have `scope: "auto-memory"` and carry `project` (the `projects/<slug>` dir name), `name` (filename), `isIndex` (true for `MEMORY.md` / `INDEX-*.md`, which sort first), and parsed `frontmatter`. They are **editable**: `PUT`/`DELETE /api/cc-config/file` accept `{ scope: "auto-memory", type: "auto-memory", project, name, content? }` and create a timestamped backup under `<memory-dir>/.cc-config-backups/auto-memory/` before mutating (an invalid `project` slug returns `EBADPROJECT`). `GET /api/cc-config/backups` lists these with `scope: "auto-memory"` and `project` set. Bodies are also readable via `GET /api/cc-config/file` (they live under `CLAUDE_HOME`).
 
-`PUT /api/cc-config/keybindings` edits `~/.claude/keybindings.json` from a structured list of context groups (`{ groups: [{ context, bindings: [{ key, action }] }] }`). The server backs the file up first (under `<CLAUDE_HOME>/cc-config-backups/keybindings/`), preserves any top-level metadata (`$schema`/`$docs`), and replaces only the `bindings` array; duplicate contexts or duplicate keys within a context return `EBADCONTENT`. Unlike `settings.json` (which the live CLI rewrites mid-session and is therefore read-only here), `keybindings.json` is safe to edit from the dashboard.
+**`PATCH /api/cc-config/settings` (key merge).** `scope` is `"user"`, `"project"`, or `"project-local"` (`settings.local.json`). `set` maps dotted key paths to JSON values; `unset` is a list of dotted key paths to delete. The server re-reads the target file **unredacted**, applies only the named keys, backs it up under `<dir>/.cc-config-backups/settings/`, and writes atomically — so keys the UI never displayed (including secret-valued ones) survive byte-for-byte. Returns `{ path, backupPath, created, changed }`. Hooks are edited through this same route, as `set: { "hooks.PreToolUse": [{ matcher, hooks: [{ type, command, timeout? }] }] }` — i.e. `settings.json`'s own nested shape, not the flattened shape `GET /hooks` returns. Errors: `EBADSCOPE` (unknown scope), `EBADNAME` (a key segment outside `[A-Za-z0-9_$][A-Za-z0-9._$-]*`, or `__proto__`/`prototype`/`constructor`), `EREDACTED` (400 — the payload contains the `<redacted>` placeholder, which would destroy a real secret), `EBADJSON` (409 — the file on disk is not valid JSON; it is left untouched rather than clobbered), `ETOOLARGE`. The project layers always resolve against the **server's** cwd; `?cwd=` is honoured on reads only, never on this write.
+
+**Plugins and marketplaces.** These five endpoints shell out to the `claude plugin …` CLI with an explicit argv array (never a shell string), pinned to the dashboard's `CLAUDE_HOME` via `CLAUDE_CONFIG_DIR`; mutating calls are serialized in-process. `source` must be `owner/repo`, an `http(s)://` URL, or an absolute path; `spec`/`key` must be `<name>` or `<name>@<marketplace>`; `scope` is `user` (default), `project` or `local`. Validation failures return 400 `EBADARG`; a missing `claude` binary returns 503 `ECLINOTFOUND`; a CLI timeout returns 504 `ETIMEOUT`; a non-zero CLI exit returns **422 `ECLIEXIT`** with the CLI's message plus `stdout`/`stderr`. Successful runs return `{ ok: true, stdout, stderr }` and broadcast `cc_config_changed`. `GET /plugins/available` proxies `claude plugin list --available --json` as `{ installed, available }`.
+
+`PUT /api/cc-config/keybindings` edits `~/.claude/keybindings.json` from a structured list of context groups (`{ groups: [{ context, bindings: [{ key, action }] }] }`). The server backs the file up first (under `<CLAUDE_HOME>/cc-config-backups/keybindings/`), preserves any top-level metadata (`$schema`/`$docs`), and replaces only the `bindings` array; duplicate contexts or duplicate keys within a context return `EBADCONTENT`. `keybindings.json` is replaced wholesale here because the live CLI does not rewrite it mid-session; `settings.json`, which it does, is only ever key-merged (see `PATCH /settings` above).
 
 Backup paths look like `<root>/cc-config-backups/<type>/<base>.<ISO>.bak[.dir]` — outside the directories Claude Code scans, so a deleted skill cannot resurface as a backup-named one. The Backups modal in the UI auto-builds `mv` restore commands.
 

docs/PLUGINS.md

@@ -426,7 +426,7 @@ These plugins query the Agent Monitor API at `http://localhost:4820`. Key data s
 Rule types: `token_threshold` (`{ total_tokens }` — the spend-relevant guardrail), `event_pattern`, `inactivity`, `status_duration`.
 
 ### Config Explorer (`/api/cc-config/*`)
-Read every Claude Code surface (skills, agents, commands, output-styles, plugins, marketplaces, mcp, hooks, settings, keybindings, statusline, memory). `memory` includes the per-project file-based store with `scope: "auto-memory"` (carrying `project`, `name`, `isIndex`, `frontmatter`); those files plus `CLAUDE.md` are mutable via `PUT`/`DELETE /api/cc-config/file` with always-on timestamped backups.
+Read every Claude Code surface (skills, agents, commands, output-styles, plugins, marketplaces, mcp, hooks, settings, keybindings, statusline, memory). `memory` includes the per-project file-based store with `scope: "auto-memory"` (carrying `project`, `name`, `isIndex`, `frontmatter`); those files plus `CLAUDE.md` are mutable via `PUT`/`DELETE /api/cc-config/file` with always-on timestamped backups. The page also **manages plugins and marketplaces**: paste a GitHub `owner/repo`, URL or local path to register a marketplace, then install / enable / disable / update / uninstall its plugins — each button runs the corresponding `claude plugin …` command on the dashboard host (argv array, never a shell string). Hooks and `settings.json` keys are editable per layer (user / project / project-local) through `PATCH /api/cc-config/settings`, a per-key merge that leaves every untouched key — including redacted secrets — exactly as it was.
 
 ## Plugin Development