test: add E2E server-detail tests and fill coverage gaps to 83.9%

- Add Playwright E2E for all 5 UX phases (Config/Missions/Mods/Players/Logs)
  with ServerDetailPage POM and fully mocked API routes
- Add logger.test.ts: dynamic module re-import pattern for level-gating tests
- Add useUpdateServer + useKillServer tests to useServers.test.tsx
- Add CreateServerPage edge cases: non-admin gate, API error handling, step 2 render
- Add auth.store rehydration and null-branch coverage tests
- Update FRONTEND.md, MODULES.md, API.md, README.md to reflect current state
  (167 unit tests, 38 E2E tests, 9 useServers hooks, all UX phases implemented)

FRONTEND.md

@@ -82,6 +82,7 @@ frontend/src/
     ├── api.test.ts                    # Axios interceptor tests
     ├── auth.store.test.ts            # Auth store tests
     ├── ui.store.test.ts              # UI store tests
+    ├── logger.test.ts                # Logger level-filtering tests
     ├── StatusLed.test.tsx            # StatusLed component tests
     ├── LoginPage.test.tsx            # Login page tests
     ├── DashboardPage.test.tsx        # Dashboard page tests
@@ -89,7 +90,11 @@ frontend/src/
     ├── ServerCard.handlers.test.tsx # Server card interaction tests
     ├── Sidebar.test.tsx              # Sidebar tests
     ├── useWebSocket.test.tsx         # WebSocket hook tests
-    └── useServers.test.tsx           # Server hooks tests
+    ├── useServers.test.tsx           # Server hooks tests (useServers, useServer, lifecycle, useUpdateServer, useKillServer)
+    ├── useServerDetail.test.tsx      # Server detail hooks (config, players, bans, missions, mods, RCon, logfiles)
+    ├── useAuth.test.tsx              # Auth hooks tests
+    ├── useGames.test.tsx             # Games hooks tests
+    └── CreateServerPage.test.tsx     # Create server wizard (steps, validation, submit, edge cases)
 ```
 
 ## Routes
@@ -281,13 +286,14 @@ Dark neumorphic theme defined in `tailwind.config.js`:
 
 ## Testing
 
-### Unit Tests (149 tests, Vitest + React Testing Library)
+### Unit Tests (167 tests, Vitest + React Testing Library)
 
 | Test File | Tests | Coverage |
 |---|---|---|
 | `api.test.ts` | 4 | Interceptors: token header, 401 redirect (non-auth), 401 no-redirect (auth) |
-| `auth.store.test.ts` | 3 | Init state, setAuth, clearAuth, localStorage sync |
+| `auth.store.test.ts` | 8 | Init state, setAuth, clearAuth, localStorage sync, rehydration, partialize |
 | `ui.store.test.ts` | 5 | Init state, toggleSidebar, setActiveServer, add/remove notifications |
+| `logger.test.ts` | 10 | All 4 log methods, level filtering (debug/warn/error), message format |
 | `StatusLed.test.tsx` | 8 | Status classes, showLabel, sizes |
 | `LoginPage.test.tsx` | 4 | Form render, validation, API call, error display |
 | `DashboardPage.test.tsx` | 5 | Loading/error/empty states, card rendering |
@@ -295,12 +301,13 @@ Dark neumorphic theme defined in `tailwind.config.js`:
 | `ServerCard.handlers.test.tsx` | 9 | Start/stop/restart success/failure notifications |
 | `Sidebar.test.tsx` | 6 | Branding, links, loading state, server list, active highlight |
 | `useWebSocket.test.tsx` | 5 | No-connect without token, connect, token in URL, invalidation, cleanup |
-| `useServers.test.tsx` | 10 | Server CRUD + lifecycle hooks, cache invalidation |
-| `useServerDetail.test.tsx` | 20+ | Config, players, bans, missions, mods, mutations, cache invalidation |
+| `useServers.test.tsx` | 12 | Server CRUD + lifecycle hooks, useUpdateServer, useKillServer |
+| `useServerDetail.test.tsx` | 20+ | Config, players, bans, missions, mods, mutations, logfiles, cache invalidation |
 | `useAuth.test.tsx` | 7 | Current user, users, change password, create/delete user, logout |
 | `useGames.test.tsx` | 5 | Games list, detail, config schema, defaults |
+| `CreateServerPage.test.tsx` | 14 | All 4 wizard steps, validation, submit, non-admin gate, API error handling |
 
-### E2E Tests (23 tests, Playwright)
+### E2E Tests (38 tests, Playwright)
 
 **Login Flow** (6 tests):
 - Display login form, branding, validation errors
@@ -315,6 +322,14 @@ Dark neumorphic theme defined in `tailwind.config.js`:
 - Player count display, server detail navigation
 - Empty state, error state
 
+**Server Detail — 5 UX phases** (15 tests, fully mocked):
+- Overview: server name/status, all 6 tabs visible
+- Config: field labels rendered (Hostname, BattlEye)
+- Missions: mission names, terrain names, Upload button
+- Mods: display names, enabled/disabled state
+- Players: player list, ping values, Kick buttons
+- Logs: collapsible Log Files section, Download buttons, live log viewer area
+
 **Full Stack Integration** (5 tests):
 - Login + see A3Master on dashboard (real backend)
 - A3Master server details in card (real backend)