fix: start replies fetch from newest, ignore stale DB timestamp

The DB-derived MAX(N.timestamp)+1 for a post is unreliable - many notes
were stored with the same timestamp (likely crawl time, not the actual
note timestamp), so passing it as before_timestamp excluded all real
replies and returned an empty notes array. Diagnostics showed two
unrelated posts coming back with identical totals (1625/1021/603) and
zero notes.

Now we start with no before_timestamp (newest page) and let pagination
walk backward via each page's last-note timestamp.

URLNotesGrabberCORE/Program.cs

@@ -452,11 +452,11 @@ namespace URLNotesGrabberCORE
             const int MaxPages = 10;
             try
             {
-                Console.WriteLine($"[Reply Text] Fetching reply text for {blogName}/{postID}/{timestamp}");
+                Console.WriteLine($"[Reply Text] Fetching reply text for {blogName}/{postID}");
 
                 int replyCount = 0;
                 int emptyReplyCount = 0;
-                long pageTimestamp = timestamp;
+                long pageTimestamp = 0;
                 int page = 0;
 
                 while (page < MaxPages)