feat: implement full backend + frontend server detail, settings, and create server pages

Backend:
- Complete FastAPI backend with 42+ REST endpoints (auth, servers, config,
  players, bans, missions, mods, games, system)
- Game adapter architecture with Arma 3 as first-class adapter
- WebSocket real-time events for status, metrics, logs, players
- Background thread system (process monitor, metrics, log tail, RCon poller)
- Fernet encryption for sensitive config fields at rest
- JWT auth with admin/viewer roles, bcrypt password hashing
- SQLite with WAL mode, parameterized queries, migration system
- APScheduler cleanup jobs for logs, metrics, events

Frontend:
- Server Detail page with 7 tabs (overview, config, players, bans,
  missions, mods, logs)
- Settings page with password change and admin user management
- Create Server wizard (4-step; known bug: silent validation failure)
- New hooks: useServerDetail, useAuth, useGames
- New components: ServerHeader, ConfigEditor, PlayerTable, BanTable,
  MissionList, ModList, LogViewer, PasswordChange, UserManager
- WebSocket onEvent callback for real-time log accumulation
- 120 unit tests passing (Vitest + React Testing Library)

Docs:
- Added .gitignore, CLAUDE.md, README.md
- Updated FRONTEND.md, ARCHITECTURE.md with current implementation state
- Added .env.example for backend configuration

Known issues:
- Create Server form: "Next" buttons don't validate before advancing,
  causing silent submit failure when fields are invalid
- Config sub-tabs need UX redesign for non-technical users

backend/core/utils/crypto.py

@@ -0,0 +1,32 @@
+"""Field-level encryption using Fernet (AES-256)."""
+from __future__ import annotations
+
+from cryptography.fernet import Fernet
+
+_fernet: Fernet | None = None
+
+
+def get_fernet() -> Fernet:
+    global _fernet
+    if _fernet is None:
+        from config import settings
+        _fernet = Fernet(settings.encryption_key.encode())
+    return _fernet
+
+
+def encrypt(plaintext: str) -> str:
+    """Encrypt plaintext string. Returns 'encrypted:<base64-token>'."""
+    token = get_fernet().encrypt(plaintext.encode()).decode()
+    return f"encrypted:{token}"
+
+
+def decrypt(ciphertext: str) -> str:
+    """Decrypt 'encrypted:<token>' string. Returns plaintext."""
+    if not ciphertext.startswith("encrypted:"):
+        return ciphertext  # Not encrypted, return as-is
+    token = ciphertext[len("encrypted:"):]
+    return get_fernet().decrypt(token.encode()).decode()
+
+
+def is_encrypted(value: str) -> bool:
+    return isinstance(value, str) and value.startswith("encrypted:")