feat: SQLite-backed installations, REST API, admin auth and web UI

Replaces the slice-2 hardcoded installation with a full install/deploy
pipeline:

- SQLite persistence (better-sqlite3) with a single `installations`
  table and a draft -> cloning -> building -> built -> starting ->
  running/error/stopped state machine; env vars and bearer tokens are
  encrypted at rest (AES-256-GCM, key derived from MASTER_KEY).
- Build/run orchestration: git clone (+ .env.example key detection),
  `nixpacks build` as a logged subprocess, dockerode container
  run/stop with forced host/port env vars and a TCP-connect health
  check before flipping an installation to "running".
- REST API (installations CRUD, build/deploy/redeploy, logs, token
  regeneration) behind single-operator session-cookie auth with a
  basic login lockout.
- Vite+React admin SPA: login, installation list, install wizard, and
  a detail page to configure env vars, trigger build/deploy/redeploy,
  view the build log, and copy the authenticated /mcp/<slug> URL.
- Dockerfile (multi-stage, pulls in nixpacks + the Docker CLI) and
  docker-compose.yml for production deployment.

Validated end-to-end against a real cloned repo: draft creation with
env-key detection, build, the error path on a failed health check, and
delete, all through the live API.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/server/package.json

@@ -8,13 +8,17 @@
     "start": "node dist/index.js"
   },
   "dependencies": {
+    "better-sqlite3": "11.10.0",
     "dockerode": "4.0.9",
     "express": "4.21.2",
+    "express-session": "1.18.1",
     "http-proxy": "1.18.1"
   },
   "devDependencies": {
+    "@types/better-sqlite3": "7.6.13",
     "@types/dockerode": "3.3.42",
     "@types/express": "4.17.23",
+    "@types/express-session": "1.18.2",
     "@types/http-proxy": "1.17.16",
     "@types/node": "24.9.1",
     "tsx": "4.20.6",