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>

utils/package-registry.js

@@ -7,6 +7,8 @@ class PackageRegistry {
     // If no dbPath provided, we'll set it during init based on current data directory
     this.dbPath = dbPath;
     this.db = null;
+    this.lastVerificationTime = 0;
+    this.verificationInterval = 5 * 60 * 1000; // 5 minutes
   }
 
   async init() {
@@ -277,6 +279,83 @@ class PackageRegistry {
       });
     }
   }
+
+  async verifyAndCleanRegistry() {
+    if (!this.db) {
+      await this.init();
+    }
+
+    const fs = require('fs').promises;
+    
+    return new Promise((resolve, reject) => {
+      this.db.all('SELECT * FROM installed_packages', async (err, rows) => {
+        if (err) {
+          reject(err);
+          return;
+        }
+
+        const toRemove = [];
+        
+        for (const row of rows) {
+          try {
+            // Check if the package still exists at the recorded path
+            await fs.access(row.install_path);
+            
+            // Additional verification for games/mods - check for key files
+            if (row.package_type === 'game') {
+              // Check for game.conf
+              const gameConfPath = require('path').join(row.install_path, 'game.conf');
+              await fs.access(gameConfPath);
+            } else if (row.package_type === 'mod') {
+              // Check for mod.conf or init.lua
+              const modConfPath = require('path').join(row.install_path, 'mod.conf');
+              const initLuaPath = require('path').join(row.install_path, 'init.lua');
+              try {
+                await fs.access(modConfPath);
+              } catch {
+                await fs.access(initLuaPath);
+              }
+            }
+          } catch (accessError) {
+            // Package directory or key files don't exist - mark for removal
+            console.log(`Package registry cleanup: Removing stale entry for ${row.author}/${row.name} (path not found: ${row.install_path})`);
+            toRemove.push(row.id);
+          }
+        }
+
+        // Remove stale entries
+        if (toRemove.length > 0) {
+          const placeholders = toRemove.map(() => '?').join(',');
+          this.db.run(`DELETE FROM installed_packages WHERE id IN (${placeholders})`, toRemove, (deleteErr) => {
+            if (deleteErr) {
+              console.error('Error cleaning up registry:', deleteErr);
+              reject(deleteErr);
+            } else {
+              console.log(`Package registry cleanup: Removed ${toRemove.length} stale entries`);
+              resolve(toRemove.length);
+            }
+          });
+        } else {
+          resolve(0);
+        }
+      });
+    });
+  }
+
+  async verifyIfNeeded() {
+    const now = Date.now();
+    if (now - this.lastVerificationTime > this.verificationInterval) {
+      try {
+        const cleaned = await this.verifyAndCleanRegistry();
+        this.lastVerificationTime = now;
+        return cleaned;
+      } catch (error) {
+        console.warn('Periodic registry verification failed:', error);
+        return 0;
+      }
+    }
+    return 0;
+  }
 }
 
 module.exports = PackageRegistry;