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/status.rs

@@ -0,0 +1,29 @@
+use crate::engine::db::Db;
+use crate::engine::service::{Sender, ServiceCtx};
+use crate::engine::state::Network;
+
+// STATUS <#channel> [nick]: show a user's access level (self if no nick).
+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: STATUS <#channel> [nick]");
+        return;
+    };
+    let Some(info) = db.channel(chan) else {
+        ctx.notice(me, from.uid, format!("\x02{chan}\x02 isn't registered."));
+        return;
+    };
+    let (label, account) = match args.get(2) {
+        Some(&nick) => (nick.to_string(), net.uid_by_nick(nick).and_then(|u| net.account_of(u)).map(str::to_string)),
+        None => (from.nick.to_string(), from.account.map(str::to_string)),
+    };
+    let level = match account.as_deref() {
+        None => "none (not logged in)",
+        Some(a) if info.founder.eq_ignore_ascii_case(a) => "founder",
+        Some(a) => match info.join_mode(a) {
+            Some("+o") => "op",
+            Some("+v") => "voice",
+            _ => "none",
+        },
+    };
+    ctx.notice(me, from.uid, format!("\x02{label}\x02 access on \x02{chan}\x02: \x02{level}\x02"));
+}