HostServ: vhost request/approval flow

REQUEST <host> records a pending vhost (typed Option<PendingVhost> on the
account, VhostRequested/VhostRequestCleared events); operators review with
WAITING and either ACTIVATE (assign + apply to online sessions) or REJECT
(clear it). Host validation and the operator gate are shared with SET.

hostserv/src/approve.rs

@@ -0,0 +1,38 @@
+use fedserv_api::{NetView, Sender, ServiceCtx, Store};
+
+// ACTIVATE <account> / REJECT <account>: approve a pending vhost request (setting
+// and applying it) or turn it down. Operators only.
+pub fn handle(me: &str, from: &Sender, args: &[&str], ctx: &mut ServiceCtx, net: &dyn NetView, db: &mut dyn Store, activate: bool) {
+    if !super::require_oper(me, from, ctx) {
+        return;
+    }
+    let Some(&account) = args.get(1) else {
+        let syntax = if activate { "Syntax: ACTIVATE <account>" } else { "Syntax: REJECT <account>" };
+        ctx.notice(me, from.uid, syntax);
+        return;
+    };
+    let host = match db.take_vhost_request(account) {
+        Ok(Some(h)) => h,
+        Ok(None) => {
+            ctx.notice(me, from.uid, format!("\x02{account}\x02 has no pending vhost request."));
+            return;
+        }
+        Err(_) => {
+            ctx.notice(me, from.uid, format!("\x02{account}\x02 isn't registered."));
+            return;
+        }
+    };
+    if !activate {
+        ctx.notice(me, from.uid, format!("Rejected \x02{account}\x02's vhost request."));
+        return;
+    }
+    match db.set_vhost(account, &host, from.nick) {
+        Ok(()) => {
+            for uid in net.uids_logged_into(account) {
+                ctx.set_host(&uid, &host);
+            }
+            ctx.notice(me, from.uid, format!("Activated vhost \x02{host}\x02 for \x02{account}\x02."));
+        }
+        Err(_) => ctx.notice(me, from.uid, "Sorry, that didn't work. Please try again in a moment."),
+    }
+}