Restore green type-check baseline (117 tests + tsc all pass)

Fixes 3 pre-existing TypeScript errors that vitest did not catch but
tsc --noEmit did:
- apps/mcp-linkedin/src/tools.test.ts: spread TOOL_NAMES before .sort()
  (readonly tuple has no mutating sort)
- packages/sanitize/src/corpus.test.ts: cast through unknown to FixtureMeta
- db/migrations/rehearse.ts: add 'postgres' driver dependency (also needed
  to run the migration itself)

Also: apps/admin test script uses --passWithNoTests (Stage 5 admin app has
no test files yet, vitest exited non-zero on empty).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

package.json

@@ -19,6 +19,7 @@
   "devDependencies": {
     "@types/node": "^22.0.0",
     "bun-types": "^1.3.12",
+    "postgres": "^3.4.5",
     "turbo": "^2.3.0",
     "typescript": "^5.7.0"
   },