feat(frontend): Implement Epic detail page with Story management

Add comprehensive Epic detail page at /epics/[id] with full CRUD operations.

Changes:
- Created Epic detail page with breadcrumb navigation
- Display Epic details: name, description, status, priority, time estimates
- Show list of Stories belonging to the Epic with card view
- Add Edit Epic functionality (opens dialog with form)
- Add Create/Edit/Delete Story functionality under Epic
- Fix Epic type inconsistency (name vs title) across components
- Update Kanban page to map Epic.name to title for unified interface
- Update epic-form to use 'name' field and add createdBy support
- Update work-item-breadcrumb to use Epic.name instead of title

Technical improvements:
- Use Shadcn UI components for consistent design
- Implement optimistic updates with React Query
- Add loading and error states with skeletons
- Follow Next.js App Router patterns with async params
- Add delete confirmation dialogs for Epic and Stories

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

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

app/(dashboard)/projects/[id]/kanban/page.tsx

@@ -125,6 +125,7 @@ export default function KanbanPage() {
     const items: KanbanWorkItem[] = [
       ...(epics || []).map((e) => ({
         ...e,
+        title: e.name, // Epic uses 'name', map to 'title' for unified interface
         type: 'Epic' as const,
       })),
       ...(stories || []).map((s) => ({