fix: skip API calls when all keys are rate-limited in -collect mode

Pre-flight check on the CollectNotes loop now sleeps until at least one
key recovers instead of issuing a wasted 429-bound request per iteration.
Extracts the countdown into ApiKeyPool.SleepUntilAnyAvailable (30s refresh)
and reuses it in CollectLikes and GrabNotes.

Co-Authored-By: Claude Opus 4.7 <[email protected]>

URLNotesGrabberCORE/DataAccess.cs

@@ -1948,6 +1948,28 @@ namespace URLNotesGrabberCORE
             return all;
         }
 
+        public static void SleepUntilAnyAvailable(int refreshSeconds = 30)
+        {
+            if (refreshSeconds <= 0) refreshSeconds = 30;
+            if (!IsAllRateLimited(out int minRetry) || minRetry <= 0) return;
+
+            DateTime retryAt = DateTime.Now.AddSeconds(minRetry);
+            int remaining = minRetry;
+            while (remaining > 0)
+            {
+                Console.WriteLine("[Pool] All API keys rate-limited. Sleeping {0}s, until {1}", remaining, retryAt.ToString("T"));
+                int sleepSeconds = Math.Min(refreshSeconds, remaining);
+                Thread.Sleep(sleepSeconds * 1000);
+                remaining -= sleepSeconds;
+
+                if (remaining > 0 && IsAllRateLimited(out int refreshed) && refreshed > 0 && refreshed < remaining)
+                {
+                    remaining = refreshed;
+                    retryAt = DateTime.Now.AddSeconds(remaining);
+                }
+            }
+        }
+
         private static void SaveState()
         {
             using var conn = new System.Data.SQLite.SQLiteConnection("Data Source=" + _dbPath);