Split BotServ and MemoServ into one-file-per-command modules

Match the NickServ/ChanServ layout: lib.rs keeps only the service struct
and the on_command dispatcher, and each command moves to its own file
bridged with #[path]. No behaviour change.

BotServ: bot.rs, assign.rs.
MemoServ: send.rs, list.rs, read.rs, del.rs.

botserv/src/bot.rs

@@ -0,0 +1,46 @@
+use fedserv_api::{Priv, Sender, ServiceCtx, Store};
+
+// BOT ADD <nick> <user> <host> [gecos] | BOT DEL <nick> | BOT LIST — manage the
+// bot registry. Administering bots is oper-only (Priv::Admin).
+pub fn handle(me: &str, from: &Sender, args: &[&str], ctx: &mut ServiceCtx, db: &mut dyn Store) {
+    if !from.privs.has(Priv::Admin) {
+        ctx.notice(me, from.uid, "Access denied — managing bots is for services operators.");
+        return;
+    }
+    match args.get(1).map(|s| s.to_ascii_uppercase()).as_deref() {
+        Some("ADD") => {
+            let (Some(&nick), Some(&user), Some(&host)) = (args.get(2), args.get(3), args.get(4)) else {
+                ctx.notice(me, from.uid, "Syntax: BOT ADD <nick> <user> <host> [gecos]");
+                return;
+            };
+            let gecos = if args.len() > 5 { args[5..].join(" ") } else { "Service Bot".to_string() };
+            match db.bot_add(nick, user, host, &gecos) {
+                Ok(()) => ctx.notice(me, from.uid, format!("Bot \x02{nick}\x02 (\x02{user}@{host}\x02) added.")),
+                Err(_) => ctx.notice(me, from.uid, format!("A bot named \x02{nick}\x02 already exists, or that didn't work.")),
+            }
+        }
+        Some("DEL") => {
+            let Some(&nick) = args.get(2) else {
+                ctx.notice(me, from.uid, "Syntax: BOT DEL <nick>");
+                return;
+            };
+            match db.bot_del(nick) {
+                Ok(true) => ctx.notice(me, from.uid, format!("Bot \x02{nick}\x02 deleted.")),
+                Ok(false) => ctx.notice(me, from.uid, format!("There's no bot named \x02{nick}\x02.")),
+                Err(_) => ctx.notice(me, from.uid, "Sorry, that didn't work. Please try again in a moment."),
+            }
+        }
+        None | Some("LIST") => {
+            let bots = db.bots();
+            if bots.is_empty() {
+                ctx.notice(me, from.uid, "No bots have been added yet. Add one with \x02BOT ADD\x02.");
+                return;
+            }
+            ctx.notice(me, from.uid, format!("Bots ({}):", bots.len()));
+            for b in &bots {
+                ctx.notice(me, from.uid, format!("  \x02{}\x02 ({}@{}) — {}", b.nick, b.user, b.host, b.gecos));
+            }
+        }
+        Some(other) => ctx.notice(me, from.uid, format!("Unknown BOT command \x02{other}\x02. Use \x02ADD\x02, \x02DEL\x02 or \x02LIST\x02.")),
+    }
+}