chanserv: topic, invite, akick, list, status

Adds the remaining moderation and listing commands. Auto-kick masks are
stored in the event log and enforced on join: a matching user is banned
and kicked. Topic and invite are sourced from the ChanServ pseudoclient.

modules/chanserv/list.rs

@@ -0,0 +1,16 @@
+use crate::engine::db::Db;
+use crate::engine::service::{Sender, ServiceCtx};
+
+// LIST: show all registered channels.
+pub fn handle(me: &str, from: &Sender, _args: &[&str], ctx: &mut ServiceCtx, db: &Db) {
+    let mut names: Vec<&str> = db.channels().map(|c| c.name.as_str()).collect();
+    if names.is_empty() {
+        ctx.notice(me, from.uid, "No channels are registered.");
+        return;
+    }
+    names.sort_unstable();
+    ctx.notice(me, from.uid, format!("Registered channels ({}):", names.len()));
+    for n in names {
+        ctx.notice(me, from.uid, format!("  \x02{n}\x02"));
+    }
+}