webui4frpc: 独立可用的可视化 frpc 控制器 (M0)

- 零 frp 源码依赖，单二进制 (Go + Vue3 + VueFlow + Element Plus)
- 画布多对多连线，渲染 tcp/udp/http/https frpc 配置
- worker 进程管理：自愈、日志轮转、崩溃退避重启
- frpc 一键安装 (GitHub Releases) + 手动指定路径
- 三页 UI：状态(默认)/连接配置/设置
- 状态页实时节点/转发状态，节点可增删改启停
- 画布冲突检查：端口/域名冲突标红 + 弹窗拦截保存
- backend 单测覆盖 store/render/process/httpapi/install
- plan.md + FRPC_FEATURES_AUDIT.md 文档

web/vite.config.ts

@@ -0,0 +1,28 @@
+import { defineConfig } from 'vite'
+import vue from '@vitejs/plugin-vue'
+import { fileURLToPath } from 'node:url'
+
+// The frontend is served by the Go binary at / (embedded dist), and talks to
+// the same origin via /api/manager/*.
+export default defineConfig({
+  plugins: [vue()],
+  base: '/',
+  resolve: {
+    alias: { '@': fileURLToPath(new URL('./src', import.meta.url)) },
+  },
+  css: {
+    preprocessorOptions: {
+      scss: {
+        additionalData: `@use "@/styles/variables.scss" as *;`,
+      },
+    },
+  },
+  build: {
+    outDir: 'dist',
+  },
+  server: {
+    proxy: {
+      '/api': 'http://127.0.0.1:17650',
+    },
+  },
+})