feat(admin): DB CRUD panel + /api/admin endpoints (#38)

- ADMIN button in the mission-control header opens a table picker + row grid with add/edit/delete (components/admin-panel.tsx), deliberately unauthenticated by explicit request
- /api/admin/tables and /api/admin/tables/{name}/rows driven off a name→table registry built from lib/db/schema.ts (lib/db/admin.ts) — no per-table code; 404 unknown table, 400 malformed payload, 409 constraint violation
- OpenAPI spec updated for all four admin operations + Admin* schemas
- unit: lib/db/admin.test.ts (registry, CRUD round-trips, composite PKs, error mapping); e2e: read-only admin.spec.ts

package.json

@@ -1,6 +1,6 @@
 {
   "name": "space-wanderer",
-  "version": "0.9.11",
+  "version": "0.9.12",
   "private": true,
   "scripts": {
     "dev": "next dev -p 3000",