iso: actually pass FELHOM_MENU/FELHOM_DEB to the repack

The repack read both correctly; the caller never set them, so a --release build reached the
narrowed R-155 guard still in 'single' mode and was refused (rc=10). Caught by the build's true
exit code. Also copies grub-release.cfg.tmpl into the brand dir and fixes the branding log line,
which claimed 'single-entry menu' unconditionally.

scripts/iso/iso-repack.sh

@@ -103,7 +103,7 @@ cp "$GCFG" "$ORIG_CFG"
 # --- 2. BRANDING + SINGLE-ENTRY MENU SURGERY (R-38) ------------------------------------------------
 #====================================================================================================
 if [[ "$BRAND" == "1" ]]; then
-    say "branding GRUB (background + single-entry menu)"
+    say "branding GRUB (background + $( [[ "$MENU" == "release" ]] && echo "two-entry INTERACTIVE release menu" || echo "single-entry menu" ))"
 
     # 2a. R-155 — the guard, NARROWED rather than removed.
     #