fix(dev): 本地 API 默认端口改为 3100 避开 Windows 保留段

Hyper-V 常保留 2960-3059，3000 会 EACCES；ensure-port-free 与 Vite 代理从 apps/api/.env 读取 PORT

apps/admin/vite.config.ts

@@ -1,6 +1,7 @@
 import { defineConfig } from 'vite';
 import vue from '@vitejs/plugin-vue';
 import { resolve } from 'path';
+import { resolveApiDevTarget } from '../../scripts/dev-api-target.mjs';
 import { visualizer } from 'rollup-plugin-visualizer';
 import AutoImport from 'unplugin-auto-import/vite';
 import Components from 'unplugin-vue-components/vite';
@@ -8,6 +9,7 @@ import { ElementPlusResolver } from 'unplugin-vue-components/resolvers';
 
 export default defineConfig(({ mode }) => {
   const analyze = process.env.ANALYZE === '1' || mode === 'analyze';
+  const apiTarget = resolveApiDevTarget();
 
   return {
   plugins: [
@@ -75,8 +77,8 @@ export default defineConfig(({ mode }) => {
   server: {
     port: 5174,
     proxy: {
-      '/api': { target: 'http://localhost:3000', changeOrigin: true },
-      '/uploads': { target: 'http://localhost:3000', changeOrigin: true },
+      '/api': { target: apiTarget, changeOrigin: true },
+      '/uploads': { target: apiTarget, changeOrigin: true },
     },
   },
 };