Fix song/application access: property not method call

ControlSurface exposes song and application as properties, not callable
methods. Replace manager.song() and manager.application() with the correct
attribute access throughout handler, application, browser, and view modules.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

AbletonOSC/handler.py

@@ -14,7 +14,7 @@ class AbletonOSCHandler:
 
     @property
     def song(self):
-        return self.manager.song()
+        return self.manager.song
 
     # ------------------------------------------------------------------
     # Registration helpers