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

mark_issue.py

@@ -17,7 +17,7 @@ if os.path.exists(venv_python) and sys.executable != venv_python:
 
 from gitea_auth import (
     get_auth_header, resolve_remote, add_remote_args,
-    api_request, repo_api_url,
+    api_request, api_get_all, repo_api_url,
 )
 
 LABEL_NAME = "status:in-progress"
@@ -45,12 +45,12 @@ def main(argv=None):
     base = repo_api_url(host, org, repo)
 
     try:
-        # Find the label ID
-        labels = api_request("GET", f"{base}/labels?limit=100", auth)
+        # Paginated inventory (#627): Gitea caps single pages at 50.
+        labels = api_get_all(f"{base}/labels", auth) or []
         label_id = None
         for lb in labels:
-            if lb["name"] == LABEL_NAME:
-                label_id = lb["id"]
+            if lb.get("name") == LABEL_NAME:
+                label_id = lb.get("id")
                 break
 
         if label_id is None: