fix: stop infinite loop when reply text is a literal dot

'.' was used as a sentinel for 'not yet fetched' in the SELECT query,
but it is also valid reply text. This caused any post where a reply
text was literally '.' to stay in the work queue forever.

Also fixes the fan-out UPDATE guard: previously it used
IFNULL(replyText, '.') <> @newValue, which would overwrite '?'
(confirmed-empty) rows with '.' when processing a dot reply elsewhere
in the reblog chain, pulling completed posts back into the queue and
causing the remaining counter to increase.

Changes:
- Remove OR replyText = '.' from GetRepliesWithFilledText SELECT
- Restrict UpdateNoteReplyText fan-out to NULL/'' rows only
- Use '?' not '.' as null-coalesce fallback in UpdateNoteReplyText

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

URLNotesGrabberCORE/DataAccess.cs

@@ -873,7 +873,7 @@ namespace URLNotesGrabberCORE
                               INNER JOIN Notes N ON N.PostID = P.PostID AND N.RootBlogName = P.BlogName
                               WHERE P.NotFound = 0
                                 AND N.type = 'reply' 
-                                AND (N.replyText IS NULL OR N.replyText = '' OR N.replyText = '.')
+                                AND (N.replyText IS NULL OR N.replyText = '')
                               GROUP BY P.BlogName, P.PostID
                               ORDER BY LatestTimestamp ASC";
 
@@ -1479,10 +1479,10 @@ namespace URLNotesGrabberCORE
 
                 //string sql = "UPDATE Notes SET replyText = @replyText WHERE rootBlogName = @rootBlogName AND PostID = @PostID AND noteBlogName = @noteBlogName AND TimeStamp = @TimeStamp AND Type = 'reply'";
                 // Match on (noteBlogName, TimeStamp ±5s) only - a reply by a given blog at a given timestamp is the same reply across the original post and every reblog of it, so this fans out across reblog chains in one shot. Tolerance absorbs the ~1s drift between what -collect stored and what mode=conversation returns now.
-                string sql = "UPDATE Notes SET replyText = @replyText, DateModified = @dateModified WHERE noteBlogName = @noteBlogName AND ABS(TimeStamp - @TimeStamp) <= 5 AND Type = 'reply' AND IFNULL(replyText, '.') <> @replyText";
+                string sql = "UPDATE Notes SET replyText = @replyText, DateModified = @dateModified WHERE noteBlogName = @noteBlogName AND ABS(TimeStamp - @TimeStamp) <= 5 AND Type = 'reply' AND (replyText IS NULL OR replyText = '')";
                 using (SQLiteCommand command = new SQLiteCommand(sql, connection))
                 {
-                    command.Parameters.AddWithValue("@replyText", replyText ?? ".");
+                    command.Parameters.AddWithValue("@replyText", replyText ?? "?");
                     command.Parameters.AddWithValue("@dateModified", DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss"));
                     command.Parameters.AddWithValue("@rootBlogName", rootBlogName);
                     command.Parameters.AddWithValue("@PostID", postID);