clean TUI core

- Stripped forced-scrollbar hack from _menu and _checklist
- Eliminated TUI_ANCHO_REFORZADO overflow across 9 files
- Removed redundant _inst() function globally
- Added dynamic list height calculation for checklists
- Introduced Desktop & Display menu (Option 12)
- Fixed non-free-firmware false positive in repo detection
- Restored terminal transparency for apt/vainfo output"

modules/gpu/_helpers.sh

@@ -190,7 +190,7 @@ offer_generic_tools() {
     if _confirm "GPU Tools" "Install monitoring and info tools?\n\n${tool_pkgs}"; then
         _run_cmd "GPU Tools" "sudo apt install -y nvtop vainfo" "Installing GPU tools..."
         vainfo
-        _pause
+        _pause "vainfo output shown above."
     else
         echo "Skipping GPU monitoring tools."
     fi

modules/gpu/amd_intel.sh

@@ -42,7 +42,7 @@ offer_amd_tools() {
         _run_cmd "AMD Tools" "sudo apt install -y ${amd_tools[*]} nvtop vainfo" "Installing AMD tools..."
     fi
     vainfo
-    _pause
+    _pause "vainfo output shown above."
 
     if $corectrl_available; then
         if [ "$DEBIAN_CODENAME" = "trixie" ]; then
@@ -109,7 +109,7 @@ offer_intel_tools() {
     if _confirm "Intel Tools" "Intel GPU monitoring tools\n\n${driver_info}\n\nPackages:\n${pkg_info}"; then
         _run_cmd "Intel Tools" "sudo apt install -y ${pkg_list[*]} vainfo" "Installing Intel monitoring tools..."
         vainfo
-        _pause
+        _pause "vainfo output shown above."
     else
         echo "Skipping Intel monitoring tools."
     fi