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/threads/metrics_collector.py

@@ -0,0 +1,118 @@
+"""
+MetricsCollectorThread — collects CPU and memory usage for a server process
+and persists to the metrics table every COLLECTION_INTERVAL seconds.
+
+Uses psutil to inspect the process identified by ProcessManager.get_pid().
+If the process is not running, the thread sleeps and retries.
+"""
+from __future__ import annotations
+
+import logging
+import queue
+
+import psutil
+
+from core.dal.metrics_repository import MetricsRepository
+from core.threads.base_thread import BaseServerThread
+
+logger = logging.getLogger(__name__)
+
+_COLLECTION_INTERVAL = 10.0
+_RETENTION_DAYS = 1
+
+
+class MetricsCollectorThread(BaseServerThread):
+    """
+    Collects process metrics for a running game server.
+
+    Args:
+        server_id: Database server ID.
+        process_manager: ProcessManager singleton instance.
+        broadcast_queue: Optional queue.Queue for real-time metric pushes.
+    """
+
+    def __init__(
+        self,
+        server_id: int,
+        process_manager,
+        broadcast_queue=None,
+    ) -> None:
+        super().__init__(server_id, "MetricsCollector")
+        self._process_manager = process_manager
+        self._broadcast_queue = broadcast_queue
+        self._psutil_process = None
+        self._samples_since_cleanup = 0
+        self._cleanup_every = 360  # ~1 hour at 10s intervals
+
+    # ── Main loop ──
+
+    def _run_loop(self) -> None:
+        pid = self._process_manager.get_pid(self.server_id)
+        if pid is None:
+            self._psutil_process = None
+            self._stop_event.wait(timeout=_COLLECTION_INTERVAL)
+            return
+
+        # Reuse or create psutil.Process handle
+        if self._psutil_process is None or self._psutil_process.pid != pid:
+            try:
+                self._psutil_process = psutil.Process(pid)
+                self._psutil_process.cpu_percent(interval=None)
+            except psutil.NoSuchProcess:
+                self._psutil_process = None
+                self._stop_event.wait(timeout=_COLLECTION_INTERVAL)
+                return
+
+        self._stop_event.wait(timeout=_COLLECTION_INTERVAL)
+
+        if self._stop_event.is_set():
+            return
+
+        try:
+            cpu_pct = self._psutil_process.cpu_percent(interval=None)
+            mem_info = self._psutil_process.memory_info()
+            mem_mb = round(mem_info.rss / (1024 * 1024), 2)
+        except psutil.NoSuchProcess:
+            logger.info("[%s] Process %d no longer exists", self.name, pid)
+            self._psutil_process = None
+            return
+        except psutil.AccessDenied as exc:
+            logger.warning("[%s] Access denied reading process %d: %s", self.name, pid, exc)
+            return
+
+        if self._db is None:
+            return
+
+        metrics_repo = MetricsRepository(self._db)
+        metrics_repo.insert(
+            server_id=self.server_id,
+            cpu_percent=cpu_pct,
+            ram_mb=mem_mb,
+        )
+        try:
+            self._db.commit()
+        except Exception as exc:
+            logger.error("[%s] DB commit failed: %s", self.name, exc)
+            self._db.rollback()
+            return
+
+        if self._broadcast_queue is not None:
+            try:
+                self._broadcast_queue.put_nowait({
+                    "type": "metrics",
+                    "server_id": self.server_id,
+                    "data": {"cpu_percent": cpu_pct, "memory_mb": mem_mb},
+                })
+            except queue.Full:
+                logger.debug("[%s] Broadcast queue full, dropping metrics event", self.name)
+
+        # Periodic cleanup
+        self._samples_since_cleanup += 1
+        if self._samples_since_cleanup >= self._cleanup_every:
+            self._samples_since_cleanup = 0
+            try:
+                metrics_repo.cleanup_old(server_id=self.server_id, retention_days=_RETENTION_DAYS)
+                self._db.commit()
+            except Exception as exc:
+                logger.warning("[%s] Cleanup failed: %s", self.name, exc)
+                self._db.rollback()