refactor: finish the AgentHub rename and drop the MCP server

Two leftovers from the rebrand, done together because they touch the same
docs and manifests.

**Data directory.** `agent-dashboard` could not simply be renamed in the
source: it names a real directory holding the live SQLite database. Startup
now moves it once, via `migrateLegacyDataDir()` in `server/lib/claude-home.js`
— a same-filesystem rename, so it is instant even at multiple gigabytes and
cannot leave two divergent copies. `getDataDir()` stays PURE and resolves to
the legacy path until the move happens; the first version of this put the
rename inside the getter, which meant `npm run test:server` relocated the
developer's real database as a side effect. The call sits behind
`require.main === module` and ahead of the router requires, because those pull
in db.js, which opens SQLite at module load. A failed rename is silent and the
old directory keeps being used: an unfashionable directory name beats a blank
database beside an unreachable one. Same treatment for the port-discovery file
(`.agent-dashboard.json` → `.agenthub.json`, old one dropped on write).

Not renamed on purpose: the Sagi localStorage keys (renaming silently resets
everyone's prefs) and the PWA manifest `id` (changing it orphans an installed
app).

**MCP server.** 4 tool calls in 46 days across 577,132 events, against 4,556
lines of TypeScript, a 2 MB committed build artifact, and a pre-commit guard
that had already blocked commits twice. Deleted: `mcp/`, the maintainer skills
and `mcp-reviewer` agent, the build check, `plugins/agenthub/.mcp.json`,
`docs/MCP.md`, 12 npm scripts, 5 Makefile targets, and every doc section
describing it.

Kept, because they are unrelated things sharing the name: the Config
Explorer's MCP tab and its API, per-lane Playwright MCP, the agenthub-config
plugin's MCP audit, and the historical `mcp__plugin_agenthub_*` events that
analytics must keep attributing.

Verified: server 1432/1432, client 459/459, tsc clean, prettier clean. Both
directions of the migration proven — a sandbox-HOME test run leaves the legacy
directory untouched, and a real boot moves it with its contents intact.

skills/file-headers/SKILL.md

@@ -24,7 +24,7 @@ that is missing the header, add it as part of the same change.
 | -------- | -------- |
 | `*.js`, `*.ts`, `*.tsx`, `*.cjs`, `*.mjs` | anything under `node_modules/`, `dist/`, `build/`, `data/` |
 | `*.py`, `*.sh` | vendored/minified files (`*.min.js`) |
-| `*.css` | generated files (they carry their own AUTO-GENERATED banner), including the committed `mcp/build/` |
+| `*.css` | generated files (they carry their own AUTO-GENERATED banner) |
 | | snapshots (`__snapshots__/`), lockfiles, JSON/YAML/Markdown |
 | | anything **gitignored** — local runtime state that happens to live in the checkout (a lane's own `.agenthub/profile/hooks/*.sh`, a scratch venv) is not this repo's source and can never be made compliant here |
 

skills/file-headers/scripts/check-headers.sh

@@ -10,8 +10,7 @@
 # differs per machine, and can never be made compliant here. Untracked files
 # are still audited, so a file an agent just wrote is caught before it is
 # staged. The extra excludes below are for paths git DOES track (or would list)
-# but the rule exempts — notably `mcp/build/`, which is committed on purpose
-# (plugin MCP servers start before anything could build them) yet is still
+# but the rule exempts — notably generated bundles, which are still
 # generated tsc output, and snapshots.
 # @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>