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.

src/contexts/UserPreferencesContext.tsx

@@ -16,6 +16,7 @@ interface UserPreferencesContextType {
   toggleObjectivesCollapse: () => Promise<void>;
   toggleTheme: () => Promise<void>;
   setTheme: (theme: 'light' | 'dark') => Promise<void>;
+  toggleFontSize: () => Promise<void>;
   
   // Column Visibility
   updateColumnVisibility: (updates: Partial<ColumnVisibility>) => Promise<void>;
@@ -90,6 +91,14 @@ export function UserPreferencesProvider({ children, initialPreferences }: UserPr
     await updateViewPreferences({ theme });
   }, [updateViewPreferences]);
 
+  const toggleFontSize = useCallback(async () => {
+    const fontSizes: ('small' | 'medium' | 'large')[] = ['small', 'medium', 'large'];
+    const currentIndex = fontSizes.indexOf(preferences.viewPreferences.fontSize);
+    const nextIndex = (currentIndex + 1) % fontSizes.length;
+    const newFontSize = fontSizes[nextIndex];
+    await updateViewPreferences({ fontSize: newFontSize });
+  }, [preferences.viewPreferences.fontSize, updateViewPreferences]);
+
   // === COLUMN VISIBILITY ===
   
   const updateColumnVisibility = useCallback(async (updates: Partial<ColumnVisibility>) => {
@@ -129,6 +138,7 @@ export function UserPreferencesProvider({ children, initialPreferences }: UserPr
     toggleObjectivesCollapse,
     toggleTheme,
     setTheme,
+    toggleFontSize,
     updateColumnVisibility,
     toggleColumnVisibility,
     isColumnVisible