feat(frontend): Implement Task management components - Sprint 4 Story 2

Add complete Task CRUD UI for Story detail page with inline creation,
status toggling, filtering, and sorting capabilities.

Changes:
- Created TaskList component with filters, sorting, and progress bar
- Created TaskCard component with checkbox status toggle and metadata
- Created TaskQuickAdd component for inline Task creation
- Added shadcn/ui checkbox and alert components
- All components use existing Task hooks (useTasks, useCreateTask, etc.)

Components:
- components/tasks/task-list.tsx (150 lines)
- components/tasks/task-card.tsx (160 lines)
- components/tasks/task-quick-add.tsx (180 lines)
- components/ui/checkbox.tsx (shadcn/ui)
- components/ui/alert.tsx (shadcn/ui)

Features:
- Task list with real-time count and progress bar
- Filter by: All, Active, Completed
- Sort by: Recent, Alphabetical, Status
- Checkbox toggle for instant status change (optimistic UI)
- Inline Quick Add form for fast Task creation
- Priority badges and metadata display
- Loading states and error handling
- Empty state messaging

Sprint 4 Story 2: Task Management in Story Detail
Task 3: Implement TaskList, TaskCard, TaskQuickAdd components

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

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

components/tasks/task-list.tsx

@@ -0,0 +1,140 @@
+'use client';
+
+import { useState } from 'react';
+import { useTasks } from '@/lib/hooks/use-tasks';
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
+import { Skeleton } from '@/components/ui/skeleton';
+import { Alert, AlertDescription } from '@/components/ui/alert';
+import { Badge } from '@/components/ui/badge';
+import { Button } from '@/components/ui/button';
+import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from '@/components/ui/select';
+import { TaskCard } from './task-card';
+import { TaskQuickAdd } from './task-quick-add';
+import { WorkItemStatus } from '@/types/project';
+
+interface TaskListProps {
+  storyId: string;
+}
+
+type FilterType = 'all' | 'active' | 'completed';
+type SortType = 'recent' | 'alphabetical' | 'status';
+
+export function TaskList({ storyId }: TaskListProps) {
+  const { data: tasks, isLoading, error } = useTasks(storyId);
+  const [filter, setFilter] = useState<FilterType>('all');
+  const [sort, setSort] = useState<SortType>('recent');
+
+  if (isLoading) {
+    return (
+      <Card>
+        <CardHeader>
+          <Skeleton className="h-8 w-48" />
+        </CardHeader>
+        <CardContent>
+          <div className="space-y-4">
+            {[1, 2, 3].map((i) => (
+              <Skeleton key={i} className="h-24 w-full" />
+            ))}
+          </div>
+        </CardContent>
+      </Card>
+    );
+  }
+
+  if (error) {
+    return (
+      <Card>
+        <CardContent className="pt-6">
+          <Alert variant="destructive">
+            <AlertDescription>
+              Failed to load tasks. Please try again.
+            </AlertDescription>
+          </Alert>
+        </CardContent>
+      </Card>
+    );
+  }
+
+  const filteredTasks = tasks?.filter(task => {
+    if (filter === 'active') return task.status !== 'Done';
+    if (filter === 'completed') return task.status === 'Done';
+    return true;
+  }) || [];
+
+  const sortedTasks = [...filteredTasks].sort((a, b) => {
+    if (sort === 'alphabetical') return a.title.localeCompare(b.title);
+    if (sort === 'status') return a.status.localeCompare(b.status);
+    return new Date(b.createdAt).getTime() - new Date(a.createdAt).getTime();
+  });
+
+  const completedCount = tasks?.filter(t => t.status === 'Done').length || 0;
+  const totalCount = tasks?.length || 0;
+  const progressPercentage = totalCount > 0 ? (completedCount / totalCount) * 100 : 0;
+
+  return (
+    <div className="space-y-6">
+      <Card>
+        <CardHeader>
+          <div className="flex items-center justify-between">
+            <div>
+              <CardTitle>Tasks</CardTitle>
+              <CardDescription>
+                {completedCount} of {totalCount} completed
+              </CardDescription>
+            </div>
+            <div className="flex items-center gap-4">
+              <Select value={filter} onValueChange={(v) => setFilter(v as FilterType)}>
+                <SelectTrigger className="w-[140px]">
+                  <SelectValue />
+                </SelectTrigger>
+                <SelectContent>
+                  <SelectItem value="all">All</SelectItem>
+                  <SelectItem value="active">Active</SelectItem>
+                  <SelectItem value="completed">Completed</SelectItem>
+                </SelectContent>
+              </Select>
+              <Select value={sort} onValueChange={(v) => setSort(v as SortType)}>
+                <SelectTrigger className="w-[160px]">
+                  <SelectValue />
+                </SelectTrigger>
+                <SelectContent>
+                  <SelectItem value="recent">Recent</SelectItem>
+                  <SelectItem value="alphabetical">Alphabetical</SelectItem>
+                  <SelectItem value="status">By Status</SelectItem>
+                </SelectContent>
+              </Select>
+            </div>
+          </div>
+          {/* Progress bar */}
+          <div className="mt-4">
+            <div className="h-2 bg-secondary rounded-full overflow-hidden">
+              <div
+                className="h-full bg-primary transition-all duration-300"
+                style={{ width: `${progressPercentage}%` }}
+              />
+            </div>
+          </div>
+        </CardHeader>
+        <CardContent className="space-y-4">
+          <TaskQuickAdd storyId={storyId} />
+
+          {sortedTasks.length === 0 ? (
+            <div className="text-center py-12">
+              <p className="text-muted-foreground">
+                {filter === 'all'
+                  ? 'No tasks yet. Create your first task above!'
+                  : `No ${filter} tasks found.`}
+              </p>
+            </div>
+          ) : (
+            <div className="space-y-3">
+              {sortedTasks.map(task => (
+                <TaskCard key={task.id} task={task} storyId={storyId} />
+              ))}
+            </div>
+          )}
+        </CardContent>
+      </Card>
+    </div>
+  );
+}