Implement CAP LS 302 flow with configurable ircv3_caps list, replacing
the minimal SASL-only registration. Parse IRCv3 message tags (@key=value)
with proper value unescaping. Add channel management plugin (kick, ban,
unban, topic, mode) and bot API methods. Add SQLite key-value StateStore
for plugin state persistence with !state inspection command.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
