ci: log gitea API error responses

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016tGMoEdMRnHsABmDbK3H7o

ci.py

@@ -33,8 +33,11 @@ def gitea(method, path, body=None):
     req.add_header("Authorization", f'token {os.environ["GH_TOKEN"]}')
     if data is not None:
         req.add_header("Content-Type", "application/json")
-    with urllib.request.urlopen(req) as resp:
-        raw = resp.read()
+    try:
+        with urllib.request.urlopen(req) as resp:
+            raw = resp.read()
+    except urllib.error.HTTPError as e:
+        sys.exit(f"gitea {method} {path}: {e.code} {e.reason}\n{e.read().decode()}")
     return json.loads(raw) if raw else None