feat(product): 实现产品需求管理模块（后端 + 前端）

后端：Product Module（CRUD）、Requirement Module（CRUD + 状态机流转）、PrismaService
前端：产品列表页、产品详情页（含需求池 Tab）、Zustand Store、API 封装

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/stores/useRequirementStore.ts

@@ -0,0 +1,66 @@
+'use client';
+
+import { create } from 'zustand';
+import { Requirement, RequirementStatus } from '@ftb/shared';
+import { api } from '@/lib/api';
+
+interface RequirementWithCreator extends Requirement {
+  creator?: { id: string; name: string };
+}
+
+interface RequirementState {
+  requirements: RequirementWithCreator[];
+  loading: boolean;
+  error: string | null;
+  statusFilter: RequirementStatus | null;
+  fetchRequirements: (productId: string, status?: RequirementStatus) => Promise<void>;
+  createRequirement: (productId: string, data: { title: string; description?: string; priority?: number; creatorId: string }) => Promise<void>;
+  updateRequirement: (productId: string, id: string, data: { title?: string; description?: string; priority?: number }) => Promise<void>;
+  updateStatus: (productId: string, id: string, status: RequirementStatus) => Promise<void>;
+  deleteRequirement: (productId: string, id: string) => Promise<void>;
+  setStatusFilter: (status: RequirementStatus | null) => void;
+}
+
+export const useRequirementStore = create<RequirementState>((set, get) => ({
+  requirements: [],
+  loading: false,
+  error: null,
+  statusFilter: null,
+
+  fetchRequirements: async (productId, status) => {
+    set({ loading: true, error: null });
+    try {
+      const query = status ? `?status=${status}` : '';
+      const requirements = await api.get<RequirementWithCreator[]>(
+        `/products/${productId}/requirements${query}`,
+      );
+      set({ requirements, loading: false });
+    } catch (e: any) {
+      set({ error: e.message, loading: false });
+    }
+  },
+
+  createRequirement: async (productId, data) => {
+    await api.post(`/products/${productId}/requirements`, data);
+    await get().fetchRequirements(productId, get().statusFilter || undefined);
+  },
+
+  updateRequirement: async (productId, id, data) => {
+    await api.patch(`/products/${productId}/requirements/${id}`, data);
+    await get().fetchRequirements(productId, get().statusFilter || undefined);
+  },
+
+  updateStatus: async (productId, id, status) => {
+    await api.patch(`/products/${productId}/requirements/${id}/status`, { status });
+    await get().fetchRequirements(productId, get().statusFilter || undefined);
+  },
+
+  deleteRequirement: async (productId, id) => {
+    await api.delete(`/products/${productId}/requirements/${id}`);
+    set({ requirements: get().requirements.filter((r) => r.id !== id) });
+  },
+
+  setStatusFilter: (status) => {
+    set({ statusFilter: status });
+  },
+}));