Root cause: apply_mention_policy() in utils.py used raw strings for
re.sub replacement arguments:
re.sub(r'<@&(\d+)>', r'@\u200brole', content)
The r-prefix makes \u200b literal backslash-u instead of Unicode ZWSP.
Python's re.sub always validates the replacement template, so \u at
position 1 raises re.error on EVERY message — even without matches.
Since _DEFAULT_NETWORK sets mention_policy.allow_role_mentions=False,
this code path runs for all networks, causing _do_relay to throw on
every single message. The exception was caught by on_message's
try/except, silently killing relay with total_messages stuck at 0.
Fix: remove r-prefix from replacement strings so \u200b is correctly
interpreted as the Unicode zero-width space character.
f1c8970d3d