chore(testing): Phase 9 — bun:test suite + CI gating with no-DB fakes

Added a real test suite (32 tests, 0 external services) using bun:test with
in-process module mocking for @mcpedia/db, @mcpedia/queue, @mcpedia/core.

Enablers:
- apps/api: extracted createApp(deps?) factory + dashboard.ts module from
  index.ts so the HTTP surface is unit-testable (real queue is lazy-imported).
- packages/core: exported shouldCreateRevision pure predicate; restoreRevision
  gained an opts.reindex seam for the chunk-rebuild contract.
- apps/mcp: renamed smoke.test.ts -> smoke.ts (bun test now owns .test.ts),
  updated stale assertions (10 tools, 4 docs in docs section).
- infra: turbo test task (cache:false), test scripts across packages,
  @types/bun + tsconfig base types, CI 'Test' step after Build.

Packages with tests: embeddings(5), parser(5), search(8), core(4),
mcp(6 auth-gates), api(8 contracts).

All green: typecheck(4/4), test(6/6 pkgs), build(web). Live API verified
/health, /metrics, /dashboard, /hooks/* auth gate on temp port.

package.json

@@ -18,10 +18,12 @@
     "worker": "/home/code/.bun/bin/bun --cwd apps/worker src/index.ts",
     "mcp": "bun --cwd apps/mcp run start",
     "mcp:http": "/home/code/.bun/bin/bun --cwd apps/mcp src/http.ts",
-    "api": "/home/code/.bun/bin/bun --cwd apps/api src/index.ts"
+    "api": "/home/code/.bun/bin/bun --cwd apps/api src/index.ts",
+    "test": "turbo run test"
   },
   "devDependencies": {
     "@trpc/client": "^11.18.0",
+    "@types/bun": "^1.3.14",
     "@types/node": "^26.2.0",
     "prettier": "^3.3.0",
     "turbo": "^2.5.0",