BotServ: TRIGGER — regex auto-responses

TRIGGER <#channel> ADD <regex>|<response> | DEL <num> | LIST | CLEAR: when
a channel line matches <regex>, the assigned bot says <response> ($nick
becomes the speaker's nick). Only the first matching trigger fires, and a
line the bot just kicked for gets no response.

Same engine machinery as badwords: patterns compile into one RegexSet per
channel (linear-time, ReDoS-safe), cached and rebuilt only on a revision
change. Patterns validated + size-limited at add time.

src/grpc.rs

@@ -139,6 +139,7 @@ fn to_wire(entry: &LogEntry) -> Option<ReplicationEvent> {
         | Event::ChannelSettingsSet { .. }
         | Event::ChannelKickerSet { .. }
         | Event::ChannelBadwordsSet { .. }
+        | Event::ChannelTriggersSet { .. }
         | Event::ChannelTopicSet { .. }
         | Event::ChannelSuspended { .. }
         | Event::ChannelUnsuspended { .. }