Merge website-branding feature and adjust for compatibility

- Resolved conflicts in models.py, app.py, and template files
- Added branding checks to prevent errors when g.branding is None
- Updated all template references to use conditional branding
- Added BrandingSettings to migrations
- Created branding uploads directory
- Integrated branding with existing comment and task management features

.gitignore

@@ -145,4 +145,8 @@ node_modules/
 
 # Temporary files
 *.tmp
-*.temp
+*.temp
+
+# User uploaded content
+static/uploads/avatars/*
+!static/uploads/avatars/.gitkeep