feat(P11-P12): 落地治理开关与移动端MVP（G0-G6/H1/M1-M4）

- 新增 Feature Flag 模型、评估服务与管理 API（erp_sync/invoice_verification）\n- 完成 ERP 与验真灰度收口（路由/服务/作业统一判定）\n- 补齐 pay 与手动 sync 的 department_id 灰度上下文\n- 增加管理后台开关页、PWA 基础设施与移动拍照/审批页面\n- 增加回归脚本、安全基线与压测脚本，更新文档与执行合同\n\nIssue: G0,G1,G2,G3,G4,G5,G6,H1,M1,M2,M3,M4

client/vite.config.ts

@@ -1,8 +1,56 @@
 import { defineConfig } from "vite";
 import react from "@vitejs/plugin-react";
+import { VitePWA } from "vite-plugin-pwa";
 
 export default defineConfig({
-  plugins: [react()],
+  plugins: [
+    react(),
+    VitePWA({
+      disable: false,
+      registerType: "autoUpdate",
+      includeAssets: ["pwa-192x192.png", "pwa-512x512.png", "pwa-maskable-512x512.png"],
+      manifest: {
+        name: "hyb-oa 移动工作台",
+        short_name: "hyb-oa",
+        description: "海音达工作台移动端入口，支持离线拍照上传与移动审批。",
+        start_url: "/",
+        display: "standalone",
+        background_color: "#ffffff",
+        theme_color: "#2563eb",
+        icons: [
+          {
+            src: "pwa-192x192.png",
+            sizes: "192x192",
+            type: "image/png",
+          },
+          {
+            src: "pwa-512x512.png",
+            sizes: "512x512",
+            type: "image/png",
+          },
+          {
+            src: "pwa-maskable-512x512.png",
+            sizes: "512x512",
+            type: "image/png",
+            purpose: "maskable",
+          },
+        ],
+      },
+      workbox: {
+        navigateFallback: "/index.html",
+        globPatterns: ["**/*.{js,css,html,ico,png,svg,webmanifest}"],
+        runtimeCaching: [
+          {
+            urlPattern: ({ url }) => url.pathname.startsWith("/api/"),
+            handler: "NetworkOnly",
+          },
+        ],
+      },
+      devOptions: {
+        enabled: false,
+      },
+    }),
+  ],
   server: {
     proxy: {
       "/api": {