101%: app-level DDoS guard, PWA, /api/health, API docs, worker JAR backup

Beyond parity — the web-feasible versions of the "host-only" items plus
extras AtomCMS doesn't have:
- App-level abuse/DDoS guard (src/lib/services/abuse-guard.ts): counts
  requests per IP and auto-adds flooders to website_ip_blacklist (enforced
  by the access guard) + fires ddosDetected(). OFF by default, tunable via
  settings. The iptables layer stays host-only; this is the real app-tier
  mitigation. Access guard now also enforces the IP blacklist (cached).
- PWA: a themeable web manifest (src/app/manifest.ts) + a service worker
  (public/sw.js, cache-first assets / network-first pages) registered after
  hydration — the hotel is now installable.
- /api/health: DB + emulator(RCON) + runtime status probe.
- /developers: a public API documentation page covering every REST endpoint
  with its method, path and auth requirement.
- jobs-worker: daily emulator JAR backup (runs host-side in the worker, like
  AtomCMS's backup command) — copies + prunes; no-ops unless EMULATOR_JAR_PATH
  + EMULATOR_BACKUP_DIR are set.

Verified live (prod, amx_test): /api/health ok, manifest + sw served, docs
page renders, normal pages unaffected by the guard. tsc 0, vitest 49/49,
next build 0.

.env.example

@@ -27,6 +27,12 @@ PASSWORD_HASH=bcrypt
 # Leave unset to disable badge uploads.
 BADGE_UPLOAD_DIR=
 
+# Emulator JAR backup job (jobs-worker, runs host-side). When both are set, the
+# worker copies the JAR daily into the backup dir, keeping the newest N.
+EMULATOR_JAR_PATH=
+EMULATOR_BACKUP_DIR=
+EMULATOR_BACKUP_KEEP=7
+
 # RCON link to the Arcturus emulator
 RCON_HOST=127.0.0.1
 RCON_PORT=3001