fix: adb 命令超时 + STF 释放失败检查，杜绝设备卡死/占用悬空

- adb 所有命令加 30s 超时：connect 到不可达地址不再无限挂起（worker 不再卡 connecting）
- STF release 检查响应状态并重试：504 等失败不再被静默吞掉，释放失败会真实上报
- release_all_mine 返回 (released, failed)；web /api/release 透出失败列表

core/stf_client.py

@@ -120,27 +120,45 @@ class STFClient:
                 return False, str(e)
         return False, "占用冲突重试耗尽"
 
-    def release(self, serial):
-        """释放设备占用（含远程断开）。"""
+    def release(self, serial, retries=3):
+        """释放设备占用。返回 (ok, msg)。
+
+        STF 释放可能因设备响应超时返回 504（如设备过载/卡死），此时设备实际未释放。
+        必须检查响应状态并重试，不能静默吞掉——否则占用会一直悬着。
+        """
         self.remote_disconnect(serial)
-        try:
-            requests.delete(f"{self.base_url}/api/v1/user/devices/{serial}",
-                            headers=self.headers, timeout=_TIMEOUT)
-        except requests.exceptions.RequestException as e:
-            _log.warning(f"释放 {serial} 请求失败: {e}")
+        last_status = None
+        last_body = ""
+        for attempt in range(1, retries + 1):
+            try:
+                r = requests.delete(f"{self.base_url}/api/v1/user/devices/{serial}",
+                                    headers=self.headers, timeout=_TIMEOUT)
+                if r.status_code in (200, 201, 202, 204):
+                    return True, "released"
+                last_status = r.status_code
+                last_body = r.text[:150]
+                _log.warning(f"释放 {serial} 失败 HTTP {r.status_code}: {last_body} ({attempt}/{retries})")
+            except requests.exceptions.RequestException as e:
+                _log.warning(f"释放 {serial} 请求异常 ({attempt}/{retries}): {e}")
+                last_status = -1
+                last_body = str(e)
+            if attempt < retries:
+                time.sleep(2)
+        return False, f"STF 释放失败(HTTP {last_status}): {last_body}"
 
     def release_all_mine(self):
-        """释放当前账户占用的所有设备（清理用）。"""
-        released = []
+        """释放当前账户占用的所有设备（清理用）。返回 (released, failed)。"""
+        released, failed = [], []
         for d in self.list_my_devices():
             serial = d["serial"]
-            try:
-                self.release(serial)
+            ok, msg = self.release(serial)
+            if ok:
                 released.append(serial)
                 _log.info(f"已释放 {serial}")
-            except Exception as e:
-                _log.error(f"释放 {serial} 失败: {e}")
-        return released
+            else:
+                failed.append(serial)
+                _log.error(f"释放 {serial} 失败: {msg}")
+        return released, failed
 
     # ================== 远程 ADB 隧道 ==================
     def remote_connect(self, serial):