feat(frontend): Refactor Kanban board to focus on Story management

Refactored the Kanban board from a mixed Epic/Story/Task view to focus exclusively on Stories, which are the right granularity for Kanban management.

Changes:
- Created StoryCard component with Epic breadcrumb, priority badges, and estimated hours display
- Updated KanbanColumn to use Story type and display epic names
- Created CreateStoryDialog for story creation with epic selection
- Added useProjectStories hook to fetch all stories across epics for a project
- Refactored Kanban page to show Stories only with drag-and-drop status updates
- Updated SignalR event handlers to focus on Story events only
- Changed UI text from 'New Issue' to 'New Story' and 'update issue status' to 'update story status'
- Implemented story status change via useChangeStoryStatus hook

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

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

lib/hooks/use-stories.ts

@@ -1,5 +1,6 @@
 import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
 import { storiesApi } from '@/lib/api/pm';
+import { epicsApi } from '@/lib/api/pm';
 import type { Story, CreateStoryDto, UpdateStoryDto, WorkItemStatus } from '@/types/project';
 import { toast } from 'sonner';
 
@@ -23,6 +24,42 @@ export function useStories(epicId?: string) {
   });
 }
 
+// Fetch all stories for a project (by fetching epics first, then all stories)
+export function useProjectStories(projectId?: string) {
+  return useQuery<Story[]>({
+    queryKey: ['project-stories', projectId],
+    queryFn: async () => {
+      if (!projectId) {
+        throw new Error('projectId is required');
+      }
+
+      console.log('[useProjectStories] Fetching all stories for project...', { projectId });
+
+      try {
+        // First fetch all epics for the project
+        const epics = await epicsApi.list(projectId);
+        console.log('[useProjectStories] Epics fetched:', epics.length);
+
+        // Then fetch stories for each epic
+        const storiesPromises = epics.map((epic) => storiesApi.list(epic.id));
+        const storiesArrays = await Promise.all(storiesPromises);
+
+        // Flatten the array of arrays into a single array
+        const allStories = storiesArrays.flat();
+        console.log('[useProjectStories] Total stories fetched:', allStories.length);
+
+        return allStories;
+      } catch (error) {
+        console.error('[useProjectStories] Fetch failed:', error);
+        throw error;
+      }
+    },
+    enabled: !!projectId,
+    staleTime: 5 * 60 * 1000, // 5 minutes
+    retry: 1,
+  });
+}
+
 export function useStory(id: string) {
   return useQuery<Story>({
     queryKey: ['stories', id],