feat: gate gitea_delete_branch on gitea.branch.delete capability (Closes #408)

Add fail-closed profile gate at tool entry before preflight or API calls,
return structured permission reports on block, and record required_permission
in delete_branch audit metadata. Regression tests prove resolver-denied
sessions cannot bypass the gate through the raw tool.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

tests/test_mcp_server.py

@@ -1005,9 +1005,19 @@ class TestReviewPR(unittest.TestCase):
 # ---------------------------------------------------------------------------
 class TestDeleteBranch(unittest.TestCase):
 
+    DELETE_PROFILE = {
+        "profile_name": "test-deleter",
+        "allowed_operations": ["gitea.read", "gitea.branch.delete"],
+        "forbidden_operations": [],
+        "audit_label": "test-deleter",
+    }
+
+    @patch("mcp_server.get_profile", return_value=DELETE_PROFILE)
     @patch("mcp_server.api_request")
     @patch("mcp_server.get_auth_header", return_value=FAKE_AUTH)
-    def test_delete_branch(self, _auth, mock_api):
+    def test_delete_branch(self, _auth, mock_api, _profile):
+        mcp_server.record_preflight_check("whoami")
+        mcp_server.record_preflight_check("capability", resolved_role="author")
         mock_api.return_value = {}
         result = gitea_delete_branch(branch="feat/branch")
         self.assertTrue(result["success"])