Implement configuration-based mod management and fix navigation spacing

## Major Features Added

### Configuration-Based Mod Management
- Implement proper Luanti mod system using load_mod_* entries in world.mt
- Add mod enable/disable via configuration instead of file copying
- Support both global mods (config-enabled) and world mods (physically installed)
- Clear UI distinction with badges: "Global (Enabled)", "World Copy", "Missing"
- Automatic registry verification to sync database with filesystem state

### Game ID Alias System
- Fix minetest_game/minetest technical debt with proper alias mapping
- Map minetest_game → minetest for world.mt files (matches Luanti internal behavior)
- Reference: c9d4c33174/src/content/subgames.cpp (L21)

### Navigation Improvements
- Fix navigation menu spacing and text overflow issues
- Change "Configuration" to "Config" for better fit
- Implement responsive font sizing with clamp() for better scaling
- Even distribution of nav buttons across full width

### Package Registry Enhancements
- Add verifyAndCleanRegistry() to automatically remove stale package entries
- Periodic verification (every 5 minutes) to keep registry in sync with filesystem
- Fix "already installed" errors for manually deleted packages
- Integration across dashboard, ContentDB, and installation workflows

## Technical Improvements

### Mod System Architecture
- Enhanced ConfigParser to handle load_mod_* entries in world.mt files
- Support for both configuration-based and file-based mod installations
- Proper mod type detection and management workflows
- Updated world details to show comprehensive mod information

### UI/UX Enhancements
- Responsive navigation with proper text scaling
- Improved mod management interface with clear action buttons
- Better visual hierarchy and status indicators
- Enhanced error handling and user feedback

### Code Quality
- Clean up gitignore to properly exclude runtime files
- Add package-lock.json for consistent dependency management
- Remove excess runtime database and log files
- Add .claude/ directory to gitignore

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

routes/contentdb.js

@@ -280,6 +280,13 @@ router.get('/updates', async (req, res) => {
 // View installed packages
 router.get('/installed', async (req, res) => {
   try {
+    // Verify and clean registry before showing installed packages
+    try {
+      await packageRegistry.verifyIfNeeded();
+    } catch (verifyError) {
+      console.warn('Registry verification failed:', verifyError);
+    }
+
     const { location } = req.query;
     const packages = await packageRegistry.getInstalledPackages(location);
     const stats = await packageRegistry.getStatistics();
@@ -384,6 +391,14 @@ router.post('/install-url', async (req, res) => {
       }
     }
     
+    // Verify registry and clean up stale entries before checking installation status
+    try {
+      await packageRegistry.verifyIfNeeded();
+    } catch (verifyError) {
+      console.warn('Registry verification failed:', verifyError);
+      // Continue anyway - don't block installation
+    }
+
     // Check if already installed at this location
     let installLocationKey;
     if (packageType === 'game') {