audit: resident website loop architecture and code quality to 10/10

Fix F1 name race with partial unique index, F2 pause/end mid-poll race with guarded updates, F3 redirect/numeric-IP SSRF, F4 quota prefix check, F5 duplicate row_get, F6 audit ternary; S1 unused import, S2 backoff doc, S3 defensive tearDown. Directed 20 pass, full 1700 pass.

cloud/tests/test_resident_website_loop.py

@@ -114,13 +114,18 @@ class WebsiteLoopTestCase(unittest.TestCase):
                 returncode=0, stdout="{}", stderr=""))
 
     def tearDown(self):
-        socket.getaddrinfo = self._orig_getaddrinfo
-        if self._old_no_proxy is None:
-            os.environ.pop("no_proxy", None)
+        # setUp 中途失败时属性可能未建：getattr 防御，避免
+        # tearDown 的 AttributeError 掩盖原始失败。
+        if getattr(self, "_orig_getaddrinfo", None) is not None:
+            socket.getaddrinfo = self._orig_getaddrinfo
+        if getattr(self, "_old_no_proxy", None) is None:
+            if "_old_no_proxy" in self.__dict__:
+                os.environ.pop("no_proxy", None)
         else:
             os.environ["no_proxy"] = self._old_no_proxy
-        if self._old_NO_PROXY is None:
-            os.environ.pop("NO_PROXY", None)
+        if getattr(self, "_old_NO_PROXY", None) is None:
+            if "_old_NO_PROXY" in self.__dict__:
+                os.environ.pop("NO_PROXY", None)
         else:
             os.environ["NO_PROXY"] = self._old_NO_PROXY
         try:
@@ -128,15 +133,27 @@ class WebsiteLoopTestCase(unittest.TestCase):
             self.content_server.server_close()
         except Exception:
             pass
-        self.content_thread.join(timeout=5)
-        self.server.shutdown()
-        self.server.server_close()
-        self.thread.join(timeout=5)
+        try:
+            self.content_thread.join(timeout=5)
+        except Exception:
+            pass
+        try:
+            self.server.shutdown()
+            self.server.server_close()
+        except Exception:
+            pass
+        try:
+            self.thread.join(timeout=5)
+        except Exception:
+            pass
         try:
             self.auth.conn.close()
         except Exception:
             pass
-        self.tmp.cleanup()
+        try:
+            self.tmp.cleanup()
+        except Exception:
+            pass
 
     def _req(self, method, path, body=None, key=None):
         conn = http.client.HTTPConnection("127.0.0.1", self.port,