Use custom Firefox user agent to avoid Cloudflare blocking

Monkey-patch truthbrush.api.USER_AGENT with Firefox 147 UA string.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/poller.py

@@ -7,8 +7,14 @@ import tempfile
 import time
 from typing import Optional
 
+import truthbrush.api
 from truthbrush import Api
 
+# Override the default user agent to avoid Cloudflare blocking
+truthbrush.api.USER_AGENT = (
+    "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:147.0) Gecko/20100101 Firefox/147.0"
+)
+
 from .database import init_db, is_post_seen, mark_post_seen
 from .discord import send_post_to_discord
 from .media import process_media