amd gcn legacy support & kernel overhaul

- Fixed Mesa 32-bit dependency conflicts by removing mesa-va-drivers from gaming setup; mesa-libgallium now includes VA-API for Mesa >= 25.3.3, resolving solver errors with backports (Mesa 26.x).
- Removed corectrl detection and installation from AMD tools in gpu/amd_intel.sh (retained in System Tools checklist only).
- Added zutty terminal emulator option alongside alacritty for Debian 12+ in terminals.sh.
- Overhauled Kernel menu: replaced "Backports Kernel" with "Kernel" submenu offering Stable, RT, Cloud, and Backports options; removed hardcoded Debian 11 restriction (backports hidden only on Bullseye); headers now installed automatically with all kernel variants; NVIDIA warnings added for Backports (DKMS required) and RT (driver compatibility note).
- Implemented AMD GCN legacy driver migration: is_amd_legacy_gcn() function detects GCN 1.0/1.1 GPUs via whitelist of 85 PCI IDs; offers user prompt to force amdgpu module with GRUB parameters (radeon.si_support=0, radeon.cik_support=0, amdgpu.si_support=1, amdgpu.cik_support=1); safe sed-based injection into GRUB_CMDLINE_LINUX_DEFAULT with backup and idempotency check.
- Standardized UI across 27 checklist locations: unified text to "Check [*] the packages you want installed/updated on your system."; removed SCROLL_HINT variable entirely from all code; changed OK button to "Apply" in _checklist() and _inputbox() only (not in _msg/_menu).
- Reordered gaming menu checklists: i386 moved to top position, steam/mangohud positioned immediately after for better dependency flow.
- Enhanced kernel installation prompts: all variants (Stable, RT, Cloud, Backports) now display candidate version numbers in parentheses using apt-cache policy and madison queries.
- update readme

modules/utils.sh

@@ -4,7 +4,6 @@
 # ------------------
 # Global variables
 # ------------------
-readonly SCROLL_HINT="  [↑↓]"
 CPU_SUMMARY=""
 RAM_SUMMARY=""
 GPU_TYPE=""
@@ -15,6 +14,7 @@ NVIDIA_GPU_DEVICE_ID=""
 HAS_NVIDIA=false
 HAS_AMD=false
 HAS_INTEL=false
+HAS_AMD_LEGACY_GCN=false
 KERNEL_VERSION=""
 DISPLAY_SERVER="unknown"
 STORAGE_SUMMARY=""
@@ -212,6 +212,7 @@ detect_gpu() {
             [ -z "$nvidia_dev_id" ] && nvidia_dev_id=$(echo "$line" | grep -oP '10de:\K[0-9a-fA-F]+' | head -n1)
         elif echo "$line" | grep -qi "amd"; then
             has_amd=true
+            HAS_AMD_LEGACY_GCN=$(is_amd_legacy_gcn)
         elif echo "$line" | grep -qi "intel"; then
             has_intel=true
             [ -z "$intel_dev_id" ] && intel_dev_id=$(echo "$line" | grep -oP '8086:\K[0-9a-fA-F]+' | head -n1)
@@ -557,11 +558,11 @@ _menu() {
 
 _checklist() {
     local title="$1" text="$2" h="$3" w="$4" lh="$5"; shift 5
-    whiptail --title "$title" --checklist "$text" "$h" "$w" "$lh" "$@" 3>&1 1>&2 2>&3 || true
+    whiptail --title "$title" --ok-button "Apply" --checklist "$text" "$h" "$w" "$lh" "$@" 3>&1 1>&2 2>&3 || true
 }
 
 _inputbox() {
-    whiptail --title "$1" --inputbox "$2" "${3:-10}" "${4:-60}" "${5:-}" 3>&1 1>&2 2>&3 || true
+    whiptail --title "$1" --ok-button "Apply" --inputbox "$2" "${3:-10}" "${4:-60}" "${5:-}" 3>&1 1>&2 2>&3 || true
 }
 
 _validate_sudoers() {