feat(frontend): Implement Epic/Story/Task Management UI (Story 2)

Complete implementation of Sprint 1 Story 2 with full CRUD operations
for Epic/Story/Task entities including forms, hierarchy visualization,
and breadcrumb navigation.

Changes:
- Add EpicForm, StoryForm, TaskForm components with Zod validation
- Implement HierarchyTree component with expand/collapse functionality
- Add WorkItemBreadcrumb for Epic → Story → Task navigation
- Create centralized exports in components/projects/index.ts
- Fix Project form schemas to match UpdateProjectDto types
- Update dashboard to remove non-existent Project.status field

API Client & Hooks (already completed):
- epicsApi, storiesApi, tasksApi with full CRUD operations
- React Query hooks with optimistic updates and invalidation
- Error handling and JWT authentication integration

Technical Implementation:
- TypeScript type safety throughout
- Zod schema validation for all forms
- React Query optimistic updates
- Hierarchical data loading (lazy loading on expand)
- Responsive UI with Tailwind CSS
- Loading states and error handling

Story Points: 8 SP
Estimated Hours: 16h
Status: Completed

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

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

components/features/projects/EditProjectDialog.tsx

@@ -31,9 +31,15 @@ const updateProjectSchema = z.object({
     .string()
     .min(1, 'Project name is required')
     .max(200, 'Project name cannot exceed 200 characters'),
+  key: z
+    .string()
+    .min(2, 'Project key must be at least 2 characters')
+    .max(10, 'Project key cannot exceed 10 characters')
+    .regex(/^[A-Z]+$/, 'Project key must contain only uppercase letters'),
   description: z
     .string()
-    .max(2000, 'Description cannot exceed 2000 characters'),
+    .max(2000, 'Description cannot exceed 2000 characters')
+    .optional(),
 });
 
 type UpdateProjectFormData = z.infer<typeof updateProjectSchema>;
@@ -55,6 +61,7 @@ export function EditProjectDialog({
     resolver: zodResolver(updateProjectSchema),
     defaultValues: {
       name: project.name,
+      key: project.key,
       description: project.description,
     },
   });
@@ -99,6 +106,29 @@ export function EditProjectDialog({
               )}
             />
 
+            <FormField
+              control={form.control}
+              name="key"
+              render={({ field }) => (
+                <FormItem>
+                  <FormLabel>Project Key</FormLabel>
+                  <FormControl>
+                    <Input
+                      placeholder="MAP"
+                      {...field}
+                      onChange={(e) => {
+                        field.onChange(e.target.value.toUpperCase());
+                      }}
+                    />
+                  </FormControl>
+                  <FormDescription>
+                    A unique identifier for the project (2-10 uppercase letters).
+                  </FormDescription>
+                  <FormMessage />
+                </FormItem>
+              )}
+            />
+
             <FormField
               control={form.control}
               name="description"