BotServ: richer TRIGGERs — capture groups + cooldown

Responses can now use $1..$9 to substitute regex capture groups (e.g.
ADD hi (\w+)|Hi $1!), and an optional trailing |<secs> sets a per-trigger
cooldown so a trigger can't be spammed. The cache compiles each pattern to
its own Regex (for captures) and tracks last-fired for the cooldown.

api/src/lib.rs

@@ -351,6 +351,7 @@ pub struct MemoView {
 pub struct TriggerView {
     pub pattern: String,
     pub response: String,
+    pub cooldown: u32,
 }
 
 #[derive(Debug, Clone)]
@@ -598,7 +599,7 @@ pub trait Store {
     // Copy one channel's BotServ config (kickers/badwords/greet/nobot) to another.
     fn copy_bot_config(&mut self, src: &str, dst: &str) -> Result<(), ChanError>;
     // Auto-response triggers (regex -> response).
-    fn trigger_add(&mut self, channel: &str, pattern: &str, response: &str) -> Result<bool, ChanError>;
+    fn trigger_add(&mut self, channel: &str, pattern: &str, response: &str, cooldown: u32) -> Result<bool, ChanError>;
     fn trigger_del(&mut self, channel: &str, index: usize) -> Result<bool, ChanError>;
     fn trigger_clear(&mut self, channel: &str) -> Result<usize, ChanError>;
     fn triggers(&self, channel: &str) -> Vec<TriggerView>;