Fix notification and sound system issues with comprehensive improvements

- **Fixed duplicate sound events**: Prevent success/shutdown sounds from playing multiple times during timeline switches and app quit
- **Added event coordination patterns**: Implemented flags and source tracking to prevent circular UI event chains
- **Completed sound event coverage**: Added missing sound methods (play_favorite, play_follow, play_unfollow, play_direct_message, play_post) and wired them to user actions
- **Enhanced notification system**: Fixed desktop notifications ignoring enable/disable settings by adding missing notifications section to default config
- **Improved timeline-specific sounds**: Conversations now use direct_message sound instead of generic timeline_update sound
- **Added duplicate code prevention guidelines**: Comprehensive CLAUDE.md section with patterns, checklist, and testing requirements to prevent future duplicate implementations
- **Sound pack compatibility**: Full support for both default pack (private_message, post_sent) and Doom pack (direct_message, post) naming conventions with intelligent fallback

All sound events now properly trigger on user actions: boost/favorite posts, follow/unfollow users, notifications, timeline updates, and lifecycle events.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

src/main_window.py

@@ -446,9 +446,9 @@ class MainWindow(QMainWindow):
         
     def on_timeline_tab_changed(self, index):
         """Handle timeline tab change"""
-        self.switch_timeline(index)
+        self.switch_timeline(index, from_tab_change=True)
         
-    def switch_timeline(self, index):
+    def switch_timeline(self, index, from_tab_change=False):
         """Switch to timeline by index with loading feedback"""
         timeline_names = ["Home", "Messages", "Mentions", "Local", "Federated", "Bookmarks", "Followers", "Following"]
         timeline_types = ["home", "conversations", "notifications", "local", "federated", "bookmarks", "followers", "following"]
@@ -457,8 +457,13 @@ class MainWindow(QMainWindow):
             timeline_name = timeline_names[index]
             timeline_type = timeline_types[index]
             
-            # Set tab to match if called from keyboard shortcut
-            if self.timeline_tabs.currentIndex() != index:
+            # Prevent duplicate calls for the same timeline
+            if hasattr(self, '_current_timeline_switching') and self._current_timeline_switching:
+                return
+            self._current_timeline_switching = True
+            
+            # Set tab to match if called from keyboard shortcut (but not if already from tab change)
+            if not from_tab_change and self.timeline_tabs.currentIndex() != index:
                 self.timeline_tabs.setCurrentIndex(index)
             
             # Announce loading
@@ -478,6 +483,10 @@ class MainWindow(QMainWindow):
                 if hasattr(self.timeline, 'sound_manager'):
                     self.timeline.sound_manager.play_error()
                 self.status_bar.showMessage(f"Failed to load {timeline_name} timeline: {str(e)}", 3000)
+            finally:
+                # Reset the flag after a brief delay to allow the operation to complete
+                from PySide6.QtCore import QTimer
+                QTimer.singleShot(100, lambda: setattr(self, '_current_timeline_switching', False))
                 
     def get_selected_post(self):
         """Get the currently selected post from timeline"""
@@ -591,6 +600,9 @@ class MainWindow(QMainWindow):
             else:
                 client.reblog_status(post.id)
                 self.status_bar.showMessage("Post boosted", 2000)
+                # Play boost sound for successful boost
+                if hasattr(self.timeline, 'sound_manager'):
+                    self.timeline.sound_manager.play_boost()
             # Refresh timeline to show updated state
             self.timeline.refresh()
         except Exception as e:
@@ -610,6 +622,9 @@ class MainWindow(QMainWindow):
             else:
                 client.favourite_status(post.id)
                 self.status_bar.showMessage("Post favorited", 2000)
+                # Play favorite sound for successful favorite
+                if hasattr(self.timeline, 'sound_manager'):
+                    self.timeline.sound_manager.play_favorite()
             # Refresh timeline to show updated state
             self.timeline.refresh()
         except Exception as e:
@@ -630,6 +645,7 @@ class MainWindow(QMainWindow):
             
     def quit_application(self):
         """Quit the application with shutdown sound"""
+        self._shutdown_sound_played = True  # Mark that we're handling the shutdown sound
         if hasattr(self.timeline, 'sound_manager'):
             self.timeline.sound_manager.play_shutdown()
             # Wait briefly for sound to start playing
@@ -761,6 +777,9 @@ class MainWindow(QMainWindow):
             client.follow_account(post.account.id)
             username = post.account.display_name or post.account.username
             self.status_bar.showMessage(f"Followed {username}", 2000)
+            # Play follow sound for successful follow
+            if hasattr(self.timeline, 'sound_manager'):
+                self.timeline.sound_manager.play_follow()
         except Exception as e:
             self.status_bar.showMessage(f"Follow failed: {str(e)}", 3000)
             
@@ -776,6 +795,9 @@ class MainWindow(QMainWindow):
             client.unfollow_account(post.account.id)
             username = post.account.display_name or post.account.username
             self.status_bar.showMessage(f"Unfollowed {username}", 2000)
+            # Play unfollow sound for successful unfollow
+            if hasattr(self.timeline, 'sound_manager'):
+                self.timeline.sound_manager.play_unfollow()
         except Exception as e:
             self.status_bar.showMessage(f"Unfollow failed: {str(e)}", 3000)
             
@@ -858,14 +880,17 @@ class MainWindow(QMainWindow):
             client.follow_account(target_account['id'])
             display_name = target_account.get('display_name') or target_account['username']
             self.status_bar.showMessage(f"Followed {display_name}", 2000)
+            # Play follow sound for successful follow
+            if hasattr(self.timeline, 'sound_manager'):
+                self.timeline.sound_manager.play_follow()
             
         except Exception as e:
             self.status_bar.showMessage(f"Follow failed: {str(e)}", 3000)
 
     def closeEvent(self, event):
         """Handle window close event"""
-        # Play shutdown sound if not already played through quit_application
-        if hasattr(self.timeline, 'sound_manager'):
+        # Only play shutdown sound if not already played through quit_application
+        if not hasattr(self, '_shutdown_sound_played') and hasattr(self.timeline, 'sound_manager'):
             self.timeline.sound_manager.play_shutdown()
             # Wait briefly for sound to complete
             from PySide6.QtCore import QTimer, QEventLoop