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.

task_capability_map.py

@@ -96,6 +96,10 @@ TASK_CAPABILITY_MAP: dict[str, dict[str, str]] = {
         "permission": "gitea.read",
         "role": "author",
     },
+    "reconcile_already_landed_pr": {
+        "permission": "gitea.pr.close",
+        "role": "reconciler",
+    },
 }
 
 # Issue-mutating MCP tools and their resolver task keys.