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.

components/HomePageClient.tsx

@@ -10,6 +10,7 @@ import { CreateTaskData } from '@/clients/tasks-client';
 import { CreateTaskForm } from '@/components/forms/CreateTaskForm';
 import { Button } from '@/components/ui/Button';
 import { JiraQuickFilter } from '@/components/kanban/JiraQuickFilter';
+import { FontSizeToggle } from '@/components/ui/FontSizeToggle';
 
 interface HomePageClientProps {
   initialTasks: Task[];
@@ -141,6 +142,9 @@ function HomePageContent() {
                   </svg>
                   {swimlanesByTags ? 'Standard' : 'Swimlanes'}
                 </button>
+                
+                {/* Font Size Toggle */}
+                <FontSizeToggle />
               </div>
               
             </div>