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>

components/features/kanban/StoryCard.tsx

@@ -0,0 +1,143 @@
+'use client';
+
+import { useSortable } from '@dnd-kit/sortable';
+import { CSS } from '@dnd-kit/utilities';
+import { Card, CardContent } from '@/components/ui/card';
+import { Badge } from '@/components/ui/badge';
+import { Avatar, AvatarFallback } from '@/components/ui/avatar';
+import { Story } from '@/types/project';
+import { FileText, FolderKanban, Clock, CheckSquare } from 'lucide-react';
+import { useMemo } from 'react';
+
+interface StoryCardProps {
+  story: Story;
+  epicName?: string;
+  taskCount?: number;
+}
+
+export function StoryCard({ story, epicName, taskCount }: StoryCardProps) {
+  const { attributes, listeners, setNodeRef, transform, transition } =
+    useSortable({ id: story.id });
+
+  const style = {
+    transform: CSS.Transform.toString(transform),
+    transition,
+  };
+
+  const priorityColors = {
+    Low: 'bg-gray-100 text-gray-700 border-gray-300',
+    Medium: 'bg-blue-100 text-blue-700 border-blue-300',
+    High: 'bg-orange-100 text-orange-700 border-orange-300',
+    Critical: 'bg-red-100 text-red-700 border-red-300',
+  };
+
+  const statusColors = {
+    Backlog: 'bg-gray-100 text-gray-600',
+    Todo: 'bg-blue-100 text-blue-600',
+    InProgress: 'bg-yellow-100 text-yellow-700',
+    Done: 'bg-green-100 text-green-700',
+  };
+
+  // Get assignee initials
+  const assigneeInitials = useMemo(() => {
+    if (!story.assigneeId) return null;
+    // For now, just use first two letters. In real app, fetch user data
+    return story.assigneeId.substring(0, 2).toUpperCase();
+  }, [story.assigneeId]);
+
+  // Calculate progress (if both estimated and actual hours exist)
+  const hoursDisplay = useMemo(() => {
+    if (story.estimatedHours) {
+      if (story.actualHours) {
+        return `${story.actualHours}/${story.estimatedHours}h`;
+      }
+      return `0/${story.estimatedHours}h`;
+    }
+    return null;
+  }, [story.estimatedHours, story.actualHours]);
+
+  return (
+    <Card
+      ref={setNodeRef}
+      style={style}
+      {...attributes}
+      {...listeners}
+      className="cursor-grab active:cursor-grabbing hover:shadow-md transition-shadow"
+    >
+      <CardContent className="p-3 space-y-2">
+        {/* Header: Story icon + Task count */}
+        <div className="flex items-center justify-between">
+          <div className="flex items-center gap-2">
+            <FileText className="w-4 h-4 text-green-600" />
+            <span className="text-xs font-medium text-gray-600">Story</span>
+          </div>
+          {taskCount !== undefined && taskCount > 0 && (
+            <Badge variant="secondary" className="text-xs">
+              <CheckSquare className="w-3 h-3 mr-1" />
+              {taskCount} {taskCount === 1 ? 'task' : 'tasks'}
+            </Badge>
+          )}
+        </div>
+
+        {/* Epic breadcrumb */}
+        {epicName && (
+          <div className="flex items-center gap-1 text-xs text-gray-500">
+            <FolderKanban className="w-3 h-3" />
+            <span className="truncate max-w-[200px]" title={epicName}>
+              {epicName}
+            </span>
+          </div>
+        )}
+
+        {/* Title */}
+        <h3 className="text-sm font-medium line-clamp-2" title={story.title}>
+          {story.title}
+        </h3>
+
+        {/* Description (if available) */}
+        {story.description && (
+          <p className="text-xs text-gray-600 line-clamp-2" title={story.description}>
+            {story.description}
+          </p>
+        )}
+
+        {/* Footer: Priority, Hours, Assignee */}
+        <div className="flex items-center justify-between pt-2 border-t">
+          <div className="flex items-center gap-2">
+            <Badge
+              variant="outline"
+              className={`${priorityColors[story.priority]} text-xs`}
+            >
+              {story.priority}
+            </Badge>
+            <Badge
+              variant="outline"
+              className={`${statusColors[story.status]} text-xs`}
+            >
+              {story.status}
+            </Badge>
+          </div>
+
+          <div className="flex items-center gap-2">
+            {/* Hours display */}
+            {hoursDisplay && (
+              <div className="flex items-center gap-1 text-xs text-gray-500">
+                <Clock className="w-3 h-3" />
+                <span>{hoursDisplay}</span>
+              </div>
+            )}
+
+            {/* Assignee avatar */}
+            {assigneeInitials && (
+              <Avatar className="h-6 w-6">
+                <AvatarFallback className="text-xs">
+                  {assigneeInitials}
+                </AvatarFallback>
+              </Avatar>
+            )}
+          </div>
+        </div>
+      </CardContent>
+    </Card>
+  );
+}