Update Web UI: Add server management scripts and improve UX

UI improvements:
- Add icon-based Execute/Edit/Delete buttons for scripts and callbacks
- Add execution result dialog with stdout/stderr and execution time
- Add favicon with media player icon
- Disable background scrolling when dialogs are open
- Add footer with author information and source code link

Backend enhancements:
- Add execution time tracking to script and callback execution
- Add /api/callbacks/execute endpoint for debugging callbacks
- Return detailed execution results (stdout, stderr, exit_code, execution_time)

Server management:
- Add scripts/start-server.bat - Start server with console window
- Add scripts/start-server-background.vbs - Start server silently
- Add scripts/stop-server.bat - Stop running server instances
- Add scripts/restart-server.bat - Restart the server

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

scripts/start-server.bat

@@ -0,0 +1,15 @@
+@echo off
+REM Media Server Startup Script
+REM This script starts the media server
+
+echo Starting Media Server...
+echo.
+
+REM Change to the media-server directory (parent of scripts folder)
+cd /d "%~dp0\.."
+
+REM Start the media server
+python -m media_server.main
+
+REM If the server exits, pause to show any error messages
+pause