BotServ: add SAY and ACT

The channel's assigned bot can now speak: SAY <#channel> <text> and ACT
<#channel> <text> (CTCP ACTION), gated on channel-operator access. Bots
are tracked in the network view so uid_by_nick resolves them, and the
message is sourced from the bot's own uid via a new ServiceCtx::privmsg.

botserv/src/say.rs

@@ -0,0 +1,35 @@
+use fedserv_api::{NetView, Priv, Sender, ServiceCtx, Store};
+
+// SAY <#channel> <text> — make the channel's assigned bot say something.
+// ACT <#channel> <text> — the same, as a CTCP ACTION (/me).
+// Requires channel-operator access (founder, op, or a services admin).
+pub fn handle(me: &str, from: &Sender, args: &[&str], ctx: &mut ServiceCtx, net: &dyn NetView, db: &dyn Store, action: bool) {
+    let verb = if action { "ACT" } else { "SAY" };
+    if args.len() < 3 {
+        ctx.notice(me, from.uid, format!("Syntax: {verb} <#channel> <text>"));
+        return;
+    }
+    let chan = args[1];
+    let text = args[2..].join(" ");
+
+    let Some(info) = db.channel(chan) else {
+        ctx.notice(me, from.uid, format!("\x02{chan}\x02 isn't registered."));
+        return;
+    };
+    let allowed = from.privs.has(Priv::Admin) || from.account.is_some_and(|a| info.is_op(a));
+    if !allowed {
+        ctx.notice(me, from.uid, format!("Access denied — you need operator access in \x02{chan}\x02."));
+        return;
+    }
+    let Some(bot) = info.assigned_bot else {
+        ctx.notice(me, from.uid, format!("\x02{chan}\x02 has no bot assigned. Assign one with \x02ASSIGN\x02 {chan} <bot>."));
+        return;
+    };
+    let Some(botuid) = net.uid_by_nick(&bot) else {
+        ctx.notice(me, from.uid, format!("Bot \x02{bot}\x02 isn't on the network right now."));
+        return;
+    };
+    let botuid = botuid.to_string();
+    let payload = if action { format!("\x01ACTION {text}\x01") } else { text };
+    ctx.privmsg(&botuid, chan, payload);
+}