feat: add prgs-reconciler profile and gated already-landed PR close (Closes #310)

Introduce a dedicated reconciler role with gitea_reconcile_already_landed_pr,
which closes open PRs only after live fetch and ancestor proof against a fresh
target branch. Document the gitea-reconciler namespace and extend task routing.

migrate_profiles.py

@@ -31,6 +31,8 @@ REVIEWER_DEFAULT_FORBIDDEN = ["branch", "commit", "push", "open_pr"]
 def infer_role(name, execution_profile):
     """Return the unambiguous role for a legacy profile name, or None."""
     haystack = f"{name} {execution_profile or ''}".lower()
+    if "reconciler" in haystack:
+        return "reconciler"
     has_author = "author" in haystack
     has_reviewer = "reviewer" in haystack
     if has_author == has_reviewer: