Phase 4: harden Sheets writes with retry-on-fail

Add retryOnFail (4 tries, 3s apart) to all Google Sheets nodes in
lead-intake and renewal-reminder so a transient API throttle/race
re-tries instead of silently dropping a row.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

n8n/lead-intake.json

@@ -70,7 +70,10 @@
           "id": "45TWPyl1wVk2Vxdm",
           "name": "SMB Google (service account)"
         }
-      }
+      },
+      "retryOnFail": true,
+      "maxTries": 4,
+      "waitBetweenTries": 3000
     },
     {
       "parameters": {
@@ -147,7 +150,10 @@
           "id": "45TWPyl1wVk2Vxdm",
           "name": "SMB Google (service account)"
         }
-      }
+      },
+      "retryOnFail": true,
+      "maxTries": 4,
+      "waitBetweenTries": 3000
     }
   ],
   "connections": {