fix(frontend): Align Epic field names with backend API

Fix frontend-backend API field mismatches for Epic entity by:
1. Changed Epic.title to Epic.name in type definitions
2. Added Epic.createdBy field (required by backend)
3. Updated all Epic references from epic.title to epic.name
4. Fixed Epic form to use name field and include createdBy

Files modified:
- types/project.ts: Updated Epic, CreateEpicDto, UpdateEpicDto interfaces
- components/epics/epic-form.tsx: Fixed defaultValues to use epic.name
- components/projects/hierarchy-tree.tsx: Replaced epic.title with epic.name
- components/projects/story-form.tsx: Fixed epic dropdown to show epic.name
- app/(dashboard)/projects/[id]/epics/page.tsx: Display epic.name in list
- app/(dashboard)/projects/[id]/page.tsx: Display epic.name in preview
- app/(dashboard)/api-test/page.tsx: Display epic.name in test page

This resolves the 400 Bad Request error when creating Epics caused by
missing 'Name' field (was sending 'title' instead) and missing 'CreatedBy' field.

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

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

app/(dashboard)/api-test/page.tsx

@@ -61,7 +61,7 @@ export default function ApiTestPage() {
           <div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-3 gap-4">
             {epics.map((epic) => (
               <Card key={epic.id} className="p-4">
-                <h3 className="font-semibold">{epic.title}</h3>
+                <h3 className="font-semibold">{epic.name}</h3>
                 {epic.description && (
                   <p className="text-sm text-gray-600 mt-1">{epic.description}</p>
                 )}