fix(engine-select): release 0.16.4

src/lib/humanize-error.js

@@ -26,7 +26,7 @@ const PATTERNS = [
   // 网络
   {
     key: 'network',
-    re: /(failed to fetch|networkerror|networkfailure|enetunreach|econnreset|econnrefused|ehostunreach|err_network|fetch failed|connection refused|connection reset|getaddrinfo|dns error|no route to host|aborted|broken pipe|connect timed out|tcp connect)/i,
+    re: /(failed to fetch|networkerror|networkfailure|enetunreach|econnreset|econnrefused|ehostunreach|err_network|fetch failed|connection refused|connection reset|getaddrinfo|dns error|no route to host|aborted|broken pipe|connect timed out|tcp connect|backend service is not running|web deployment mode|后端服务未运行)/i,
   },
   // Gateway 未启动（特殊的 connection refused / port not listen 情况）
   {

src/lib/tauri-api.js

@@ -231,7 +231,13 @@ export async function checkBackendHealth() {
   if (isTauriRuntime()) { _setBackendOnline(true); return true }
   try {
     const resp = await fetch('/__api/health', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: '{}' })
-    const ok = resp.ok
+    const ct = (resp.headers.get('content-type') || '').toLowerCase()
+    if (!resp.ok || !ct.includes('application/json')) {
+      _setBackendOnline(false)
+      return false
+    }
+    const data = await resp.json().catch(() => null)
+    const ok = !!data?.ok
     _setBackendOnline(ok)
     return ok
   } catch {