Fix subtitle module not switching view on drop from main menu

- Changed handleSubtitlesModuleDrop to call showModule("subtitles")
- Previously only refreshed if already in subtitles view (s.active == "subtitles")
- When dropping from main menu, s.active was "mainmenu", so view never switched
- Now matches behavior of compare and inspect modules
- Video path will now properly populate when dragging from main menu

Generated with [Claude Code](https://claude.com/claude-code)

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

subtitles_module.go

@@ -537,10 +537,8 @@ func (s *appState) handleSubtitlesModuleDrop(items []fyne.URI) {
 		}
 	}
 
-	// Refresh the view to show the loaded files
-	if s.active == "subtitles" {
-		s.showSubtitlesView()
-	}
+	// Switch to subtitles module to show the loaded files
+	s.showModule("subtitles")
 }
 
 func (s *appState) loadSubtitleFile(path string) error {