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/contentdb/index.ejs

@@ -279,13 +279,13 @@ document.addEventListener('DOMContentLoaded', function() {
             const result = await response.json();
             
             if (result.success) {
-                showStatus(result.message + ' ✅', 'success', false);
+                showStatus(result.message + ' ✅ Redirecting to Extensions...', 'success', false);
                 clearForm();
                 
-                // Auto-hide success message after 5 seconds
+                // Redirect to extensions page after 2 seconds to show the newly installed package
                 setTimeout(() => {
-                    installStatus.style.display = 'none';
-                }, 5000);
+                    window.location.href = '/extensions';
+                }, 2000);
             } else {
                 showStatus(result.error || 'Installation failed', 'error', false);
             }