feat(frontend): 构建前端 MVP，实现完整 UI 框架与 mock 数据层

- 安装 zustand + react-router-dom 依赖
- 修复 Vite 代理配置，添加 /auth 路由转发
- 实现 API 封装层（client.ts 统一 fetch、auth.ts 真实调用）
- 实现 mock 数据层（mock.ts 模拟 WebSocket 管线进度）
- 实现 4 个 zustand stores（auth/project/task/generation）
- 实现 5 个组件（StyleSelector/PromptEditor/GenerateForm/ProgressBar/AssetPreview）
- 实现 5 个页面（Login/Register/Project/Generate/Result）
- 实现路由含 ProtectedRoute 守卫
- 添加暗色主题全局样式
- 更新前端文档与 API 文档

frontend/src/stores/generation.ts

@@ -0,0 +1,82 @@
+import { create } from 'zustand'
+import type { Asset, PipelineProgress, PipelineStage } from '../api/types'
+import { submitGenerate } from '../api/generate'
+import { createMockWebSocket } from '../api/mock'
+
+type Status = 'idle' | 'submitting' | 'running' | 'completed' | 'failed'
+
+interface GenerationState {
+  taskId: string | null
+  stage: PipelineStage | null
+  progress: number
+  status: Status
+  retryCount: number
+  rejectReason: string | null
+  assets: Asset[]
+  error: string | null
+  submit: (projectId: string, prompt: string, assetType: string) => Promise<void>
+  handleProgress: (msg: PipelineProgress) => void
+  reset: () => void
+}
+
+let cleanupWs: (() => void) | null = null
+
+export const useGenerationStore = create<GenerationState>((set, get) => ({
+  taskId: null,
+  stage: null,
+  progress: 0,
+  status: 'idle',
+  retryCount: 0,
+  rejectReason: null,
+  assets: [],
+  error: null,
+
+  submit: async (projectId, prompt, assetType) => {
+    set({ status: 'submitting', error: null })
+    try {
+      const taskId = await submitGenerate(projectId, prompt, assetType)
+      set({ taskId, status: 'running', progress: 0 })
+
+      // 启动 mock WebSocket
+      cleanupWs = createMockWebSocket(
+        taskId,
+        (msg) => get().handleProgress(msg),
+        (assets) => {
+          set({ status: 'completed', assets, progress: 100 })
+        },
+        (error) => {
+          set({ status: 'failed', error })
+        }
+      )
+    } catch (err) {
+      set({ status: 'failed', error: (err as Error).message })
+    }
+  },
+
+  handleProgress: (msg) => {
+    set({
+      stage: msg.stage,
+      progress: msg.progress,
+      retryCount: msg.retryCount ?? get().retryCount,
+      rejectReason: msg.rejectReason ?? null,
+    })
+    if (msg.result?.assets) {
+      set({ assets: msg.result.assets })
+    }
+  },
+
+  reset: () => {
+    cleanupWs?.()
+    cleanupWs = null
+    set({
+      taskId: null,
+      stage: null,
+      progress: 0,
+      status: 'idle',
+      retryCount: 0,
+      rejectReason: null,
+      assets: [],
+      error: null,
+    })
+  },
+}))