feat(sync): add Octokit retry/throttle and rate-limited status

packages/backend/convex/schema.ts

@@ -119,6 +119,7 @@ const applicationTables = {
         v.literal('checking'),
         v.literal('conflict'),
         v.literal('error'),
+        v.literal('rate_limited'),
       ),
     ),
     upstreamAheadBy: v.optional(v.number()),