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>

views/dashboard.ejs

@@ -22,7 +22,7 @@ const body = `
         <div class="stat-value" style="font-size: 1rem; word-break: break-all;">
             ${stats.minetestDir}
         </div>
-        <div class="stat-label">Minetest Directory</div>
+        <div class="stat-label">Data Directory</div>
     </div>
 </div>
 
@@ -95,7 +95,7 @@ const body = `
                     <td>${systemInfo.nodeVersion}</td>
                 </tr>
                 <tr>
-                    <td><strong>Minetest Directory</strong></td>
+                    <td><strong>Data Directory</strong></td>
                     <td style="word-break: break-all;">${stats.minetestDir}</td>
                 </tr>
                 <tr>