🚩 Add feature flags system with configuration, state management, conditional rendering, developer tools, router integration, and comprehensive testing

docs/projects/Pokedex.Online/PROGRESS.md

@@ -279,6 +279,48 @@ npm test -- useAsyncState
 - Updated `switchApiVersion()` to reset all async states
 - Result: Cleaner state management, consistent error handling pattern
 
+### Step 10-12: Feature Flags System Implementation
+
+**Feature Flag Configuration:**
+- Created comprehensive flag definitions in `src/config/feature-flags.js`
+- 9 feature flags defined: gamemaster features, challonge features, developer tools, UI features
+- Each flag includes: name, description, enabled state, required permissions, tags
+- Support for both development and production environments
+
+**useFeatureFlags Composable:**
+- Full state management with local overrides (developer mode)
+- Permission-based flag checking (integrates with useAuth)
+- Methods: `isEnabled()`, `toggle()`, `getFlags()`, `setBackendFlags()`, `fetchFromBackend()`
+- Persists overrides to localStorage
+- Reactive flag state updates
+
+**FeatureFlag Component:**
+- Wrapper component for conditional rendering: `<FeatureFlag flag="name">`
+- Supports fallback slot for disabled state
+- Clean API for hiding/showing features throughout app
+- Fully reactive to flag changes
+
+**Developer Tools Panel:**
+- Beautiful slide-up panel with Ctrl+Shift+D shortcut
+- Toggle any feature flag with live override badges
+- Display authentication status, role, permissions
+- Environment info (mode, version, API endpoints)
+- Reset all overrides functionality
+- Integrated into App.vue root component
+
+**Router Integration:**
+- Updated `src/router/guards.js` to check feature flags
+- Routes can specify `meta: { featureFlag: 'flag-name' }`
+- Automatically blocks navigation to disabled features
+- Redirects to home when flag is off
+- Works alongside existing auth guards
+
+**Testing:**
+- 7 tests for useFeatureFlags composable
+- 7 tests for FeatureFlag component (render, fallback, reactivity)
+- 8 tests for router guards (feature flags + auth protection)
+- All 22 new tests passing ✅
+
 **Testing:**
 - All 91 existing tests continue to pass
 - Build verification successful (no syntax errors)