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/invite.rs

@@ -0,0 +1,26 @@
+use crate::engine::db::Db;
+use crate::engine::service::{Sender, ServiceCtx};
+use crate::engine::state::Network;
+
+// INVITE <#channel> [nick]: invite a user (self if no nick) into the channel.
+pub fn handle(me: &str, from: &Sender, args: &[&str], ctx: &mut ServiceCtx, net: &Network, db: &Db) {
+    let Some(&chan) = args.get(1) else {
+        ctx.notice(me, from.uid, "Syntax: INVITE <#channel> [nick]");
+        return;
+    };
+    if !super::require_op(me, from, chan, ctx, db) {
+        return;
+    }
+    let target = match args.get(2) {
+        Some(&nick) => match net.uid_by_nick(nick) {
+            Some(u) => u.to_string(),
+            None => {
+                ctx.notice(me, from.uid, format!("\x02{nick}\x02 isn't here."));
+                return;
+            }
+        },
+        None => from.uid.to_string(),
+    };
+    ctx.invite(me, &target, chan);
+    ctx.notice(me, from.uid, format!("Invited to \x02{chan}\x02."));
+}