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.

server/README.md

@@ -67,7 +67,6 @@ graph TB
     
     subgraph "Clients"
         Browser[Web Browser]
-        MCP[MCP Clients]
     end
     
     CC --> Hooks
@@ -80,7 +79,6 @@ graph TB
     APIRouter --> DB
     
     WSServer -->|Real-time events| Browser
-    MCP -->|HTTP| APIRouter
     
     style Express fill:#000000,color:#fff
     style DB fill:#003B57,color:#fff
@@ -1454,7 +1452,7 @@ test("POST /api/hooks/event ingests hook payload", async () => {
 
 ## Terminal Access (`agenthub` CLI)
 
-Everything this server exposes over REST is also reachable from a terminal via the repo's dependency-free `agenthub` CLI (`bin/agenthub.js`, linked by `npm run setup`): monitoring (`health`/`stats`/`kanban`/`tail`), data browsing, analytics/workflows/cost, lane adoption and managed-worktree provisioning (`lanes add --cwd` / `lanes add --repo`), fact-confirmed lane reset/removal/purge (`lanes reset|remove|purge <id> --yes`), alerts + webhook tests, pricing CRUD, imports, and administration (`doctor`/`export`/`cleanup`/`reinstall-hooks`/`update-check`/`clear-data --yes`). It resolves the live server through the same `~/.claude/.agent-dashboard.json` registry the hook handler uses. See [docs/CLI.md](../docs/CLI.md).
+Everything this server exposes over REST is also reachable from a terminal via the repo's dependency-free `agenthub` CLI (`bin/agenthub.js`, linked by `npm run setup`): monitoring (`health`/`stats`/`kanban`/`tail`), data browsing, analytics/workflows/cost, lane adoption and managed-worktree provisioning (`lanes add --cwd` / `lanes add --repo`), fact-confirmed lane reset/removal/purge (`lanes reset|remove|purge <id> --yes`), alerts + webhook tests, pricing CRUD, imports, and administration (`doctor`/`export`/`cleanup`/`reinstall-hooks`/`update-check`/`clear-data --yes`). It resolves the live server through the same `~/.claude/.agenthub.json` registry the hook handler uses. See [docs/CLI.md](../docs/CLI.md).
 
 ## Deployment
 
@@ -1528,10 +1526,10 @@ LOG_LEVEL=info                     # Log level (debug, info, warn, error)
 NODE_ENV=production node server/index.js
 
 # With PM2 (process manager)
-pm2 start server/index.js --name agent-dashboard
+pm2 start server/index.js --name agenthub
 
 # With systemd
-sudo systemctl start agent-dashboard
+sudo systemctl start agenthub
 ```
 
 ### Docker Deployment
@@ -1562,8 +1560,8 @@ CMD ["node", "server/index.js"]
 
 ```bash
 # Build and run
-docker build -t agent-dashboard .
-docker run -p 127.0.0.1:4820:4820 -v "$HOME/.claude/agent-dashboard:/app/data" agent-dashboard
+docker build -t agenthub .
+docker run -p 127.0.0.1:4820:4820 -v "$HOME/.claude/agenthub:/app/data" agenthub
 ```
 
 ---