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>

packages/sanitize/src/corpus.test.ts

@@ -27,7 +27,7 @@ const parseFixture = (name: string, raw: string): Fixture => {
   if (!m) throw new Error(`Fixture ${name} missing frontmatter`);
   const fmRaw = m[1]!;
   const body = m[2]!;
-  const meta = parseSimpleYaml(fmRaw) as FixtureMeta;
+  const meta = parseSimpleYaml(fmRaw) as unknown as FixtureMeta;
   return { name, meta, body };
 };