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/servers/missions_router.py

@@ -0,0 +1,115 @@
+"""Mission management endpoints — list, upload, delete mission files."""
+from __future__ import annotations
+
+import logging
+from typing import Annotated
+
+from fastapi import APIRouter, Depends, HTTPException, UploadFile, File, status
+from sqlalchemy.engine import Connection
+
+from adapters.exceptions import AdapterError
+from adapters.registry import GameAdapterRegistry
+from core.servers.service import ServerService
+from database import get_db
+from dependencies import get_current_user, require_admin
+
+logger = logging.getLogger(__name__)
+
+router = APIRouter(prefix="/servers/{server_id}/missions", tags=["missions"])
+
+_MAX_UPLOAD_SIZE = 500 * 1024 * 1024  # 500 MB
+
+
+def _ok(data):
+    return {"success": True, "data": data, "error": None}
+
+
+def _get_mission_manager(server_id: int, game_type: str):
+    """Get MissionManager for the server's game type."""
+    adapter = GameAdapterRegistry.get(game_type)
+    if not adapter.has_capability("mission_manager"):
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail={"code": "NOT_SUPPORTED", "message": f"Game type '{game_type}' does not support mission management"},
+        )
+    return adapter.get_mission_manager(server_id)
+
+
+@router.get("")
+def list_missions(
+    server_id: int,
+    db: Annotated[Connection, Depends(get_db)],
+    _user: Annotated[dict, Depends(get_current_user)],
+) -> dict:
+    """List all available mission files on disk."""
+    server = ServerService(db).get_server(server_id)  # raises 404 if not found
+    mgr = _get_mission_manager(server_id, server["game_type"])
+    try:
+        missions = mgr.list_missions()
+    except AdapterError as exc:
+        raise HTTPException(status_code=500, detail={"code": "ADAPTER_ERROR", "message": str(exc)})
+
+    return _ok({
+        "server_id": server_id,
+        "missions": missions,
+        "total": len(missions),
+    })
+
+
+@router.post("", status_code=status.HTTP_201_CREATED)
+async def upload_mission(
+    server_id: int,
+    db: Annotated[Connection, Depends(get_db)],
+    _admin: Annotated[dict, Depends(require_admin)],
+    file: UploadFile = File(...),
+) -> dict:
+    """
+    Upload a mission .pbo file.
+    Max size: 500 MB.
+    """
+    server = ServerService(db).get_server(server_id)  # raises 404 if not found
+
+    if not file.filename:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail={"code": "NO_FILENAME", "message": "No filename provided"},
+        )
+
+    content = await file.read()
+    if len(content) > _MAX_UPLOAD_SIZE:
+        raise HTTPException(
+            status_code=status.HTTP_413_REQUEST_ENTITY_TOO_LARGE,
+            detail={"code": "FILE_TOO_LARGE", "message": f"File too large. Max size is {_MAX_UPLOAD_SIZE // (1024*1024)} MB"},
+        )
+
+    mgr = _get_mission_manager(server_id, server["game_type"])
+    try:
+        mission = mgr.upload_mission(file.filename, content)
+    except AdapterError as exc:
+        raise HTTPException(status_code=400, detail={"code": "ADAPTER_ERROR", "message": str(exc)})
+
+    return _ok(mission)
+
+
+@router.delete("/{filename}")
+def delete_mission(
+    server_id: int,
+    filename: str,
+    db: Annotated[Connection, Depends(get_db)],
+    _admin: Annotated[dict, Depends(require_admin)],
+) -> dict:
+    """Delete a mission file by filename."""
+    server = ServerService(db).get_server(server_id)  # raises 404 if not found
+    mgr = _get_mission_manager(server_id, server["game_type"])
+    try:
+        deleted = mgr.delete_mission(filename)
+    except AdapterError as exc:
+        raise HTTPException(status_code=400, detail={"code": "ADAPTER_ERROR", "message": str(exc)})
+
+    if not deleted:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail={"code": "NOT_FOUND", "message": f"Mission '{filename}' not found"},
+        )
+
+    return _ok({"message": f"Mission '{filename}' deleted"})