Fix server management issues and improve overall stability

Major server management fixes:
- Replace Flatpak-specific pkill with universal process tree termination using pstree + process.kill()
- Fix signal format errors (SIGTERM/SIGKILL instead of TERM/KILL strings)
- Add 5-second cooldown after server stop to prevent race conditions with external detection
- Enable Stop Server button for external servers in UI
- Implement proper timeout handling with process tree killing

ContentDB improvements:
- Fix download retry logic and "closed" error by preventing concurrent zip extraction
- Implement smart root directory detection and stripping during package extraction
- Add game-specific timeout handling (8s for VoxeLibre vs 3s for simple games)

World creation fixes:
- Make world creation asynchronous to prevent browser hangs
- Add WebSocket notifications for world creation completion status

Other improvements:
- Remove excessive debug logging
- Improve error handling and user feedback throughout the application
- Clean up temporary files and unnecessary logging

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

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

utils/package-registry.js

@@ -3,12 +3,20 @@ const path = require('path');
 const fs = require('fs').promises;
 
 class PackageRegistry {
-  constructor(dbPath = 'data/packages.db') {
+  constructor(dbPath = null) {
+    // If no dbPath provided, we'll set it during init based on current data directory
     this.dbPath = dbPath;
     this.db = null;
   }
 
   async init() {
+    // Set database path based on current data directory if not already set
+    if (!this.dbPath) {
+      const paths = require('./paths');
+      await paths.initialize();
+      this.dbPath = path.join(paths.minetestDir, 'luhost_packages.db');
+    }
+    
     // Ensure data directory exists
     const dir = path.dirname(this.dbPath);
     await fs.mkdir(dir, { recursive: true });
@@ -24,6 +32,24 @@ class PackageRegistry {
     });
   }
 
+  async reinitialize() {
+    // Close existing database connection
+    if (this.db) {
+      await new Promise((resolve) => {
+        this.db.close((err) => {
+          if (err) console.error('Error closing database:', err);
+          resolve();
+        });
+      });
+    }
+    
+    // Clear the path so it gets recalculated
+    this.dbPath = null;
+    
+    // Reinitialize with new path
+    return this.init();
+  }
+
   async createTables() {
     const sql = `
       CREATE TABLE IF NOT EXISTS installed_packages (