fix(integrations): pin api_call to the SSRF-validated IP (#5727)

* fix(integrations): pin api_call to the SSRF-validated IP

execute_api_call runs check_outbound_url on the target, but that guard only
resolves the host to answer (ok, reason) and hands back no address. The request
right after it opened a plain httpx.AsyncClient, which resolves the host again at
connect time. A base_url host on a low TTL can pass the guard as a public IP and
then flip to 169.254.169.254 for the connect, so the call lands on cloud metadata
with the integration's stored auth headers attached.

Resolve once, remember the IPs the guard actually validated, and pin the client's
socket to that set through a small AnyIO-backed transport. SNI and the Host header
still come from the URL, so TLS and vhost routing are unchanged; connect-time
fallback stays inside the approved address set over one shared deadline. This is
the same pinning the webhook sender and web-fetch paths already do -- api_call was
the last outbound path that skipped it.

Fixes #5513

* fix(integrations): de-duplicate the pinned IP list

_default_resolver calls getaddrinfo(host, None) with no socktype filter, so
glibc returns one record per socktype and a single-homed host comes back three
times over. _validated_ips kept every entry, so the transport pinned the same
address repeatedly and the connect fallback could spend its shared deadline
retrying one dead address instead of moving on to a genuinely different one.

Windows getaddrinfo collapses those duplicate records, which is why the
ip-literal pin test only failed on CI and not locally.

tests/test_integrations_api_call_truncation.py

@@ -83,9 +83,10 @@ async def _call(json_data, status=200):
     with (
         patch.object(integrations, "_find_integration", return_value=DUMMY_INTEGRATION),
         patch("httpx.AsyncClient", return_value=mock_client),
-        # api.example.com doesn't resolve; the SSRF guard would fail closed.
-        # These tests are about truncation, so stub the guard open.
-        patch("src.url_safety.check_outbound_url", return_value=(True, "ok")),
+        # api.example.com doesn't resolve. Point the resolver at a public
+        # address instead of stubbing the guard open, so the real check (and
+        # the connect-IP pinning that reads its result) still runs.
+        patch("src.url_safety._default_resolver", lambda host: ["93.184.216.34"]),
     ):
         return await integrations.execute_api_call("test_integ", "GET", "/items")
 
@@ -101,9 +102,10 @@ async def _call_with_integration(integration, path="/items"):
     with (
         patch.object(integrations, "_find_integration", return_value=integration),
         patch("httpx.AsyncClient", return_value=mock_client),
-        # api.example.com doesn't resolve; the SSRF guard would fail closed.
-        # These tests are about URL joining, so stub the guard open.
-        patch("src.url_safety.check_outbound_url", return_value=(True, "ok")),
+        # api.example.com doesn't resolve. Point the resolver at a public
+        # address instead of stubbing the guard open, so the real check (and
+        # the connect-IP pinning that reads its result) still runs.
+        patch("src.url_safety._default_resolver", lambda host: ["93.184.216.34"]),
     ):
         result = await integrations.execute_api_call("test_integ", "GET", path)
     return result, mock_client