feat(plugin): install the pipelines' skill plugins on SessionStart

The ship-feature pipelines drive `/superpowers:*` commands as their per-node
drivers, so a fresh install had a dependency it was only told about — the
`/ccam-doctor` WARN row and a line in the README.

`server/lib/skill-plugins.js` now carries the whole thing, shared by the
doctor (reports) and the bootstrap (installs) so the two cannot disagree
about what is missing. The bootstrap installs at the very end of its DETACHED
worker — the install clones from the network and nothing in the 10 s
SessionStart hook may wait on it — retrying once behind a `marketplace add`,
logging a failure with the manual command, and never throwing: the dashboard,
hooks, CLI and MCP all work without these plugins. The outcome is recorded as
`state.skillPluginsSettled`, which `fastPathOk()` now also requires, so the
check runs exactly once per install and `/ccam-update` is the retry.
`CCAM_AUTO_INSTALL_PLUGINS=0|false|off` opts out.

Reporting is derived, installing is allowlisted. Requirements come from the
loaded templates, which is right for a report; installing from that same
source would not be, because a template is a file anyone can drop into
`DASHBOARD_PIPELINES_DIR` — it would turn "edit a JSON file" into "run this
vendor's install command on the next session". Auto-install consults
`AUTO_INSTALLABLE`, a constant in code (`superpowers` today), and reports
every other requirement as skipped.

Tests inject a `run` seam so no case reaches a real `claude plugin install`,
and cover the refusal explicitly.

CLAUDE.md

@@ -1,6 +1,6 @@
 # Claude Code Working Guide
 
-_Last synced: e109d28 (2026-09-04) + Workspace single console render site._ A change that makes any statement in this file, `AGENTS.md`, or a README wrong — a moved path, a new or changed extension point, a retired rule — updates that file in the same change-set and bumps this marker.
+_Last synced: e109d28 (2026-09-04) + Workspace single console render site + skill-plugin auto-install._ A change that makes any statement in this file, `AGENTS.md`, or a README wrong — a moved path, a new or changed extension point, a retired rule — updates that file in the same change-set and bumps this marker.
 
 ## Project mission
 - Maintain a reliable local-first dashboard for Claude Code session monitoring.
@@ -14,6 +14,7 @@ _Last synced: e109d28 (2026-09-04) + Workspace single console render site._ A ch
 - `mcp/`: local MCP server exposing dashboard operations as tools. **`mcp/build/` is committed on purpose** — plugin MCP servers start before any bootstrap could build them; `scripts/check-mcp-build.js` (content hash in `mcp/build/.srchash`, run by pre-commit and `/ccam-doctor`) keeps it honest. Rebuild with `npm run mcp:build`, never hand-edit `mcp/build/`.
 - `skills/`: this repo's skills. Because the repo root **is** the `ccam` plugin root, this is also the plugin's skills directory — every skill here ships to anyone who installs the plugin, addressed as `/ccam:<name>` (bare `/<name>` works as an alias). Put a skill here only if it should reach plugin users; `ccam skills install` remains a fallback that copies `ship-feature-lane` into `~/.claude/skills/` for plain checkouts. - `agents/`: the same story for subagents — plugin root, so all five (`qc-local`, `senior-gate-reviewer`, `backend-reviewer`, `frontend-reviewer`, `mcp-reviewer`) ship as `ccam:<name>`. This is also the source `ccam lanes agents install` copies the two pipeline agents from into a lane's `.claude/agents/`, which is what keeps the bare `subagent_type: qc-local` working there. One file per agent, never a second copy.
 - `.claude-plugin/`: the marketplace plus the root `ccam` plugin manifest (`"source": "./"` — the whole repo is the plugin). Its hooks are inline in `plugin.json`; its commands live in `plugins/ccam/commands/`, which is NOT a subdirectory plugin. `scripts/plugin-bootstrap.js` runs from `SessionStart` and owns the writable runtime under `~/.claude/agent-dashboard/runtime/` — it never writes into the plugin cache, which Claude Code replaces on every update. See `docs/PLUGINS.md`.
+- **Reporting a required plugin is derived; installing one is allowlisted.** `server/lib/skill-plugins.js` reads the `/plugin:skill` strings out of the loaded pipeline templates — right for the `/ccam-doctor` row, wrong for an install: a template is a file anyone can drop into `DASHBOARD_PIPELINES_DIR`, so installing whatever name it contains would make "edit a JSON file" mean "run this vendor's install command next session". The bootstrap installs only what `AUTO_INSTALLABLE` (a constant in that file, `superpowers` today) lists, in its DETACHED worker, never in the 10 s hook, recorded once as `state.skillPluginsSettled` (also gating `fastPathOk`), never throwing, and off under `CCAM_AUTO_INSTALL_PLUGINS=0|false|off`. Do not derive an install target from a template.
 
 ## Lanes