fix: paginate repository-label inventory for gitea_set_issue_labels (#627)

Replace single-page GET labels?limit=100 with api_get_all-backed
_repo_label_id_map so later-page labels (e.g. type:feature,
workflow-hardening) are not falsely rejected during full-set replacement.

Also add post-mutation verification, fix related MCP/CLI label inventory
call sites, and add multi-page regression tests for the #601 reconciler
failure mode.

Closes #627

manage_labels.py

@@ -22,7 +22,7 @@ venv_python = os.path.join(PROJECT_ROOT, "venv", "bin", "python3")
 if os.path.exists(venv_python) and sys.executable != venv_python:
     os.execv(venv_python, [venv_python] + sys.argv)
 
-from gitea_auth import get_auth_header, api_request, repo_api_url
+from gitea_auth import get_auth_header, api_request, api_get_all, repo_api_url
 import issue_workflow_labels
 
 HOST = "gitea.dadeschools.net"
@@ -82,9 +82,17 @@ def api(method, path, auth, payload=None):
 
 
 def _labels_by_name(auth):
-    """Return {label name: id} for the repo's existing labels."""
-    existing = api("GET", "/labels?limit=100", auth) or []
-    return {lb["name"]: lb["id"] for lb in existing}
+    """Return {label name: id} for the repo's existing labels (all pages, #627)."""
+    existing = api_get_all(f"{BASE_URL}/labels", auth) or []
+    name_to_id = {}
+    for lb in existing:
+        if not isinstance(lb, dict):
+            continue
+        name = lb.get("name")
+        lid = lb.get("id")
+        if name and lid is not None and name not in name_to_id:
+            name_to_id[name] = lid
+    return name_to_id
 
 
 def create_labels(auth, dry=False):