fix(auth): route delete_branch capability to the reconciler role (Closes #729)

Remote post-merge branch deletion was blocked because the capability
resolver classified delete_branch as an author-role task while
gitea.branch.delete is granted only to prgs-reconciler. No configured
profile could satisfy both the permission gate and the role gate, so
every deletion failed closed with performed=false.

Re-home delete_branch from the author role to the reconciler role in
both single-source-of-truth maps:
  - task_capability_map.TASK_CAPABILITY_MAP["delete_branch"].role
  - role_session_router: TASK_REQUIRED_ROLE + AUTHOR_TASKS/RECONCILER_TASKS

resolve_task_capability("delete_branch") now resolves to prgs-reconciler.
In gitea_delete_branch, the reconciler is now the delete-capable role and
performs raw deletion through the existing reconciliation-cleanup-phase
authorization gate (operator approval + safe_to_delete proof) plus the
preservation/protected guards; the prior reconciler->cleanup redirect is
removed as it would orphan that guarded flow. Author, reviewer, and
merger stay denied by the permission gate and the required-role gate.
gitea_cleanup_merged_pr_branch remains a separate reconciler-owned path
with independent merged/ancestry/ownership verification.

Tests: reconciler resolves + performs eligible deletion; author/reviewer/
merger denied even when holding the permission; protected/preservation
branches remain fail-closed; both role maps asserted in agreement.
Updated pre-existing tests that encoded the superseded author-delete /
#687 reconciler-redirect contract. Full suite: 3190 passed, 6 skipped,
1 pre-existing unrelated failure (test_issue_702 create_pr stale-binding).

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01UracxyRHQw49rZBaexHdft

gitea_mcp_server.py

@@ -8559,31 +8559,18 @@ def gitea_delete_branch(
         }
 
     # Possessing gitea.branch.delete alone is not enough for arbitrary deletion.
-    # task_capability_map maps delete_branch → author; reconciler must use the
-    # guarded cleanup_merged_pr_branch path only (#687 / #514).
+    # #729: task_capability_map maps delete_branch → reconciler (only the
+    # reconciler profile holds gitea.branch.delete). The reconciler performs raw
+    # deletion through the reconciliation-cleanup-phase authorization gate below
+    # (operator approval + safe_to_delete proof), which is the sanctioned
+    # authorized-cleanup role for raw branch deletion (#514/#687). Author,
+    # reviewer, and merger are denied by the permission gate above and, even if
+    # they somehow hold the permission, by the required-role gate here.
+    # gitea_cleanup_merged_pr_branch remains a separate reconciler-owned path
+    # with independent merged/ancestry/ownership verification.
     profile = get_profile()
     active_role = _profile_role_kind(profile)
     required_role = task_capability_map.required_role("delete_branch")
-    if active_role == "reconciler":
-        return {
-            "success": False,
-            "performed": False,
-            "required_permission": "gitea.branch.delete",
-            "required_role_kind": required_role,
-            "active_role_kind": active_role,
-            "reasons": [
-                "reconciler profile cannot use raw gitea_delete_branch; "
-                "use gitea_cleanup_merged_pr_branch for a fully merged PR "
-                "source branch only (fail closed)"
-            ],
-            "exact_next_action": (
-                "Call gitea_cleanup_merged_pr_branch with pr_number, the "
-                "exact PR head branch, and confirmation "
-                "'CLEANUP MERGED PR <n> BRANCH <branch>' after capability "
-                "resolve for cleanup_merged_pr_branch."
-            ),
-            "permission_report": _permission_block_report("gitea.branch.delete"),
-        }
     if active_role != required_role:
         return {
             "success": False,