feat: improve installer with custom icon, launch-after-install, and running-instance detection

- Use custom icon.ico for installer/uninstaller UI
- LaunchApp opens server then browser after install
- .onInit detects running instance and offers to stop it
- Use WMIC-based process kill targeting embedded Python path
- start-hidden.vbs prefers embedded Python over system Python
- Add pystray dependency to build script
- CLAUDE.md: note to consult CI/CD guide for build changes

scripts/start-hidden.vbs

@@ -1,7 +1,13 @@
+Set fso = CreateObject("Scripting.FileSystemObject")
 Set WshShell = CreateObject("WScript.Shell")
 ' Get the directory of this script (scripts\), then go up to media-server root
-scriptDir = CreateObject("Scripting.FileSystemObject").GetParentFolderName(WScript.ScriptFullName)
-serverRoot = CreateObject("Scripting.FileSystemObject").GetParentFolderName(scriptDir)
+scriptDir = fso.GetParentFolderName(WScript.ScriptFullName)
+serverRoot = fso.GetParentFolderName(scriptDir)
 WshShell.CurrentDirectory = serverRoot
-' Run python completely hidden (0 = hidden, False = don't wait)
-WshShell.Run "python -m media_server.main", 0, False
+' Use embedded Python if present (installed distribution), otherwise system Python
+embeddedPython = serverRoot & "\python\python.exe"
+If fso.FileExists(embeddedPython) Then
+    WshShell.Run """" & embeddedPython & """ -m media_server.main", 0, False
+Else
+    WshShell.Run "python -m media_server.main", 0, False
+End If