Fix sunrise window logging and Mattermost cleanup scope

daily_sunrise_video.sh:
- Fix "Sunrise (UTC)" label — sunrise.py has always returned local time;
  now labelled correctly as "Sunrise (local)"
- After image selection, log first and last frame timestamps alongside the
  overlay time so the window can be verified at a glance:
    Images: 481  (05:22:10 → 06:43:00  overlay: 06:32)

sunrise2mm.py:
- Cleanup now only deletes posts whose message matches "Sunrise YYYY-MM-DD"
  (the format this script posts), so other posts with attachments in the
  channel are never touched

https://claude.ai/code/session_01C4jbd3waXG3eKZYbGUjLUQ

sunrise2mm.py

@@ -146,6 +146,9 @@ while True:
             continue
         if not post.get('file_ids'):
             continue
+        # Only delete posts this script created — message starts with "Sunrise YYYY-MM-DD"
+        if not re.match(r'^Sunrise \d{4}-\d{2}-\d{2}', post.get('message', '')):
+            continue
         if post['create_at'] >= cutoff_ms:
             continue
         del_r = requests.delete(