refactor: clean up service implementations and remove dead code

src/main.py

@@ -1,3 +1,4 @@
+import atexit
 import os
 
 from fabric import Application
@@ -88,6 +89,15 @@ def main():
     app.set_css = set_css
     app.set_css()
 
+    def cleanup_css_monitors():
+        for m in css_monitors:
+            try:
+                m.cancel()
+            except Exception:
+                pass
+
+    atexit.register(cleanup_css_monitors)
+
     # Inject into the executing module's namespace (__main__)
     # to emulate what happened when this file was run directly.
     # This allows fabric-cli exec to execute commands flawlessly.