Silence SC2024 on the nmtui redirect, with the reason recorded

shellcheck flags 'sudo doesn't affect redirects', which matters when redirecting into a
root-owned file. /dev/tty is the invoking user's own controlling terminal and the redirect
is what gives nmtui a terminal at all, so the warning does not apply here.

Also drop a stale message referencing a forge that a generic install has no knowledge of.

firstboot.sh

@@ -37,10 +37,14 @@ net_up() { ping -c1 -W3 "${GITEA_SSH_HOST:-archlinux.org}" >/dev/null 2>&1; }
 # --- network: prompt + help connect if needed (nmtui, since NetworkManager is installed) ---
 require_network() {
     net_up && return
-    echo "No network / can't reach Gitea."
+    echo "No network yet."
     local ans
     while ! net_up; do
         read -rp ">> Type 'net' to open nmtui, or connect another way then press Enter: " ans </dev/tty || true
+        # SC2024 warns that sudo doesn't apply to redirects — which matters when redirecting
+        # into a root-owned file. /dev/tty is this user's own controlling terminal, and the
+        # redirect exists to hand nmtui a terminal at all. Not applicable.
+        # shellcheck disable=SC2024
         [ "$ans" = net ] && sudo nmtui </dev/tty >/dev/tty 2>&1 || true
     done
 }