Group the module crates under modules/

The service pseudo-clients and the ircd protocol link sat flat at the
repo root, mixed in with the daemon core and the SDK. Move them all
under modules/ so the tree separates concerns cleanly: the daemon in
src/, the SDK every module links against in api/, and the loadable
modules — the pseudo-clients plus the protocol link — in modules/.

Workspace members, the daemon's per-crate dependency paths, and each
module's api path are updated to match; the docs follow. No code change.

modules/hostserv/src/set.rs

@@ -0,0 +1,36 @@
+use fedserv_api::{parse_duration, NetView, Sender, ServiceCtx, Store};
+
+// SET <account> <host> [duration]: assign a vhost to an account, applying it at
+// once to online sessions. An optional duration (e.g. 30d) makes it temporary.
+// Operators only.
+pub fn handle(me: &str, from: &Sender, args: &[&str], ctx: &mut ServiceCtx, net: &dyn NetView, db: &mut dyn Store) {
+    if !super::require_oper(me, from, ctx) {
+        return;
+    }
+    let (Some(&account), Some(&host)) = (args.get(1), args.get(2)) else {
+        ctx.notice(me, from.uid, "Syntax: SET <account> <host> [duration]");
+        return;
+    };
+    if db.account(account).is_none() {
+        ctx.notice(me, from.uid, format!("\x02{account}\x02 isn't registered."));
+        return;
+    }
+    let host = match super::prepare_vhost(host, account, db) {
+        Ok(h) => h,
+        Err(msg) => {
+            ctx.notice(me, from.uid, msg);
+            return;
+        }
+    };
+    let ttl = args.get(3).and_then(|s| parse_duration(s));
+    match db.set_vhost(account, &host, from.nick, ttl) {
+        Ok(()) => {
+            for uid in net.uids_logged_into(account) {
+                ctx.apply_vhost(&uid, &host);
+            }
+            let when = args.get(3).filter(|_| ttl.is_some()).map(|d| format!(" (expires in {d})")).unwrap_or_default();
+            ctx.notice(me, from.uid, format!("Vhost \x02{host}\x02 assigned to \x02{account}\x02{when}."));
+        }
+        Err(_) => ctx.notice(me, from.uid, "Sorry, that didn't work. Please try again in a moment."),
+    }
+}