feat: add font size toggle functionality

- Implemented a FontSizeToggle component in HomePageClient for adjusting task font sizes in kanban views.
- Updated TaskCard to apply dynamic font size classes based on user preferences.
- Enhanced user preferences to include font size settings, defaulting to 'medium'.
- Modified TODO.md to mark the font size toggle task as complete.

lib/types.ts

@@ -70,7 +70,8 @@ export interface ViewPreferences {
   showFilters: boolean;
   objectivesCollapsed: boolean;
   theme: 'light' | 'dark';
-  [key: string]: boolean | 'tags' | 'priority' | 'light' | 'dark' | undefined;
+  fontSize: 'small' | 'medium' | 'large';
+  [key: string]: boolean | 'tags' | 'priority' | 'light' | 'dark' | 'small' | 'medium' | 'large' | undefined;
 }
 
 export interface ColumnVisibility {