Update agent prompt to use new atomic thread tool and add testing mode

- Replace deprecated bluesky_reply instruction with add_post_to_bluesky_reply_thread
- Provide clear guidance on atomic threading approach (multiple calls = thread)
- Add testing mode with --test flag to prevent actual posting and queue deletion
- Implement duplicate detection in queue to prevent reprocessing in test mode
- Update tool detection to terminate bot if deprecated bluesky_reply is used
- Add comprehensive testing mode logging with 🧪 indicators

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[e-mail]>

bsky.py

···
 
 The YAML above shows the complete conversation thread. The most recent post is the one mentioned above that you should respond to, but use the full thread context to understand the conversation flow.
 
-Use the bluesky_reply tool to send a response less than 300 characters."""
+To reply, use the add_post_to_bluesky_reply_thread tool. Call it multiple times to create a threaded reply:
+- Each call adds one post to the reply thread (max 300 characters per post)
+- Use multiple calls to build longer responses across several posts
+- Example: First call for opening thought, second call for elaboration, etc."""
 
         # Extract all handles from notification and thread data
         all_handles = set()