ci: run the integration suites inside the stack's own network

The suites connected to localhost:<published port>, which works for a developer
but not on a containerised runner: published ports live in the host's network
namespace, so the runner container gets connection refused.

Run them from inside the stack instead, against the gateway by service name.
SITE_BASE_URL and SITE_HOST_HEADER make that possible without weakening what is
under test: the Host stays "localhost", so the gateway's host check and
TrustedHostMiddleware see exactly what a localhost run produces, and the tests
that deliberately send their own Host still override it.

S3_PUBLIC_ENDPOINT has to agree, because presigned URLs are signed against it
and the signature covers the host, so it cannot be rewritten afterwards. CI
points the whole stack at http://storage:9000 so the URLs it hands out are
reachable by whoever follows them.

The browser suites still need Chrome to reach the stack from the runner, which
the same namespace split prevents. They now check reachability and skip with a
warning instead of failing with a bare connection error; recorded as ROADMAP
5.10, since they are the only coverage for the artwork editor.

Verified both ways: the six suites pass inside the network, and an unchanged
developer localhost run still passes, as do both browser suites locally.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

local/security_test.py

@@ -5,10 +5,10 @@ from urllib.error import HTTPError
 from urllib.request import Request, urlopen
 from urllib.parse import urlparse, parse_qs
 from uuid import uuid4
-from .smoke_test import Client, BASE
+from .smoke_test import Client, BASE, with_host
 
 def raw(path, expected, headers=None, body=None):
-    request=Request(BASE+path, data=body, headers=headers or {})
+    request=Request(BASE+path, data=body, headers=with_host(headers))
     try:
         with urlopen(request,timeout=10) as response:
             assert response.status==expected

local/smoke_test.py

@@ -18,7 +18,19 @@ if Path('.env').exists():
         if line.strip() and not line.startswith('#') and '=' in line:
             key,value=line.split('=',1)
             os.environ.setdefault(key,value)
-BASE='http://localhost:'+os.environ.get('SITE_PORT','8080')
+# CI runs these from a container on the stack's own network, because a runner
+# container cannot reach ports published on the host's loopback. SITE_BASE_URL
+# points at the gateway by service name; SITE_HOST_HEADER keeps the Host the
+# gateway and TrustedHostMiddleware expect, so the security configuration under
+# test stays identical to a developer's localhost run.
+BASE=os.environ.get('SITE_BASE_URL') or 'http://localhost:'+os.environ.get('SITE_PORT','8080')
+HOST_HEADER=os.environ.get('SITE_HOST_HEADER')
+
+def with_host(headers=None):
+    headers=dict(headers or {})
+    if HOST_HEADER and not any(k.lower()=='host' for k in headers):
+        headers['Host']=HOST_HEADER
+    return headers
 
 class Client:
     def __init__(self):
@@ -26,7 +38,7 @@ class Client:
         self.opener=build_opener(HTTPCookieProcessor(self.jar))
         self.operator_client=None
     def call(self,path,body=None,operator=False,expected=200):
-        headers={'Content-Type':'application/json'}
+        headers=with_host({'Content-Type':'application/json'})
         if operator:
             if self.operator_client is None:
                 self.operator_client=Client()