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

scripts/dev-api-target.mjs

@@ -0,0 +1,28 @@
+import { existsSync, readFileSync } from 'node:fs';
+import { dirname, resolve } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const repoRoot = resolve(dirname(fileURLToPath(import.meta.url)), '..');
+
+/** 本地 dev 默认端口；3000 在部分 Windows（Hyper-V 保留 2960–3059）上会 EACCES */
+const DEFAULT_DEV_API_PORT = '3100';
+
+/** 与 apps/api/.env 的 PORT 对齐 */
+export function resolveApiDevPort() {
+  if (process.env.PORT) return String(process.env.PORT);
+
+  let port = DEFAULT_DEV_API_PORT;
+  const envPath = resolve(repoRoot, 'apps/api/.env');
+  if (existsSync(envPath)) {
+    const match = readFileSync(envPath, 'utf8').match(/^PORT=(\d+)\s*$/m);
+    if (match) port = match[1];
+  }
+  return port;
+}
+
+/** 供 player/admin Vite 代理使用 */
+export function resolveApiDevTarget() {
+  if (process.env.VITE_DEV_API_TARGET) return process.env.VITE_DEV_API_TARGET;
+  if (process.env.API_DEV_TARGET) return process.env.API_DEV_TARGET;
+  return `http://localhost:${resolveApiDevPort()}`;
+}