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-quick-add.tsx

@@ -0,0 +1,190 @@
+'use client';
+
+import { useState } from 'react';
+import { useForm } from 'react-hook-form';
+import { zodResolver } from '@hookform/resolvers/zod';
+import { z } from 'zod';
+import { useCreateTask } from '@/lib/hooks/use-tasks';
+import { CreateTaskDto, WorkItemPriority } from '@/types/project';
+import { Button } from '@/components/ui/button';
+import { Input } from '@/components/ui/input';
+import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from '@/components/ui/select';
+import {
+  Form,
+  FormControl,
+  FormField,
+  FormItem,
+  FormLabel,
+  FormMessage,
+} from '@/components/ui/form';
+import { Card, CardContent } from '@/components/ui/card';
+import { Plus, X } from 'lucide-react';
+
+interface TaskQuickAddProps {
+  storyId: string;
+}
+
+const taskSchema = z.object({
+  title: z.string().min(1, 'Title is required').max(200, 'Title too long'),
+  priority: z.enum(['Critical', 'High', 'Medium', 'Low']),
+  estimatedHours: z.coerce.number().min(0).optional(),
+});
+
+type TaskFormData = z.infer<typeof taskSchema>;
+
+export function TaskQuickAdd({ storyId }: TaskQuickAddProps) {
+  const [isOpen, setIsOpen] = useState(false);
+  const createTask = useCreateTask();
+
+  const form = useForm<TaskFormData>({
+    resolver: zodResolver(taskSchema),
+    defaultValues: {
+      title: '',
+      priority: 'Medium',
+      estimatedHours: undefined,
+    },
+  });
+
+  const onSubmit = async (data: TaskFormData) => {
+    const taskData: CreateTaskDto = {
+      storyId,
+      title: data.title,
+      priority: data.priority as WorkItemPriority,
+      estimatedHours: data.estimatedHours,
+    };
+
+    createTask.mutate(taskData, {
+      onSuccess: () => {
+        form.reset();
+        // Keep form open for batch creation
+      },
+    });
+  };
+
+  const handleCancel = () => {
+    form.reset();
+    setIsOpen(false);
+  };
+
+  if (!isOpen) {
+    return (
+      <Button
+        onClick={() => setIsOpen(true)}
+        variant="outline"
+        className="w-full"
+        size="sm"
+      >
+        <Plus className="w-4 h-4 mr-2" />
+        Add Task
+      </Button>
+    );
+  }
+
+  return (
+    <Card className="border-dashed">
+      <CardContent className="pt-4">
+        <Form {...form}>
+          <form onSubmit={form.handleSubmit(onSubmit)} className="space-y-4">
+            <div className="flex items-center justify-between mb-2">
+              <h4 className="text-sm font-medium">Quick Add Task</h4>
+              <Button
+                type="button"
+                variant="ghost"
+                size="sm"
+                onClick={handleCancel}
+                className="h-6 w-6 p-0"
+              >
+                <X className="w-4 h-4" />
+              </Button>
+            </div>
+
+            <FormField
+              control={form.control}
+              name="title"
+              render={({ field }) => (
+                <FormItem>
+                  <FormLabel>Title *</FormLabel>
+                  <FormControl>
+                    <Input
+                      placeholder="e.g., Implement login API"
+                      {...field}
+                      autoFocus
+                    />
+                  </FormControl>
+                  <FormMessage />
+                </FormItem>
+              )}
+            />
+
+            <div className="grid grid-cols-2 gap-4">
+              <FormField
+                control={form.control}
+                name="priority"
+                render={({ field }) => (
+                  <FormItem>
+                    <FormLabel>Priority</FormLabel>
+                    <Select
+                      onValueChange={field.onChange}
+                      defaultValue={field.value}
+                    >
+                      <FormControl>
+                        <SelectTrigger>
+                          <SelectValue placeholder="Select priority" />
+                        </SelectTrigger>
+                      </FormControl>
+                      <SelectContent>
+                        <SelectItem value="Critical">Critical</SelectItem>
+                        <SelectItem value="High">High</SelectItem>
+                        <SelectItem value="Medium">Medium</SelectItem>
+                        <SelectItem value="Low">Low</SelectItem>
+                      </SelectContent>
+                    </Select>
+                    <FormMessage />
+                  </FormItem>
+                )}
+              />
+
+              <FormField
+                control={form.control}
+                name="estimatedHours"
+                render={({ field }) => (
+                  <FormItem>
+                    <FormLabel>Est. Hours</FormLabel>
+                    <FormControl>
+                      <Input
+                        type="number"
+                        placeholder="8"
+                        {...field}
+                        value={field.value ?? ''}
+                      />
+                    </FormControl>
+                    <FormMessage />
+                  </FormItem>
+                )}
+              />
+            </div>
+
+            <div className="flex gap-2">
+              <Button
+                type="submit"
+                size="sm"
+                disabled={createTask.isPending}
+                className="flex-1"
+              >
+                {createTask.isPending ? 'Creating...' : 'Add Task'}
+              </Button>
+              <Button
+                type="button"
+                variant="outline"
+                size="sm"
+                onClick={handleCancel}
+              >
+                Cancel
+              </Button>
+            </div>
+          </form>
+        </Form>
+      </CardContent>
+    </Card>
+  );
+}