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/gpu.sh

@@ -87,6 +87,21 @@ _install_amd_intel_stack() {
         install_amd_firmware
     fi
 
+    if $HAS_AMD_LEGACY_GCN; then
+        local msg="An AMD GCN 1.0/GCN 1.1 GPU has been detected.\n\n"
+        msg+="These old GPUs use the legacy 'radeon' driver by default,\n"
+        msg+="but the modern 'amdgpu' driver offers better performance\n"
+        msg+="and Mesa support.\n\n"
+        msg+="Would you like to FORCE the amdgpu driver?\n"
+        msg+="(adds radeon.si_support=0 radeon.cik_support=0\n"
+        msg+=" amdgpu.si_support=1 amdgpu.cik_support=1 to GRUB)"
+        if _confirm "AMD Legacy GCN" "$msg" 16 72; then
+            _apply_amd_gcn_grub_fix
+        else
+            echo "Skipping amdgpu migration."
+        fi
+    fi
+
     _install_mesa_backports
 
     local mesa_ver
@@ -109,6 +124,33 @@ _install_amd_intel_stack() {
     _msg "Graphics Stack — Complete" "$summary" 12 65
 }
 
+_apply_amd_gcn_grub_fix() {
+    local file="/etc/default/grub"
+    local backup="${file}.backup.gcn.$(date +%Y%m%d_%H%M%S)"
+    local params="radeon.si_support=0 radeon.cik_support=0 amdgpu.si_support=1 amdgpu.cik_support=1"
+
+    if grep -q "amdgpu.si_support=1" "$file" 2>/dev/null; then
+        _msg "AMD GCN" "amdgpu parameters already present in GRUB.\nNo changes made." 8 50
+        return
+    fi
+
+    sudo cp "$file" "$backup"
+
+    sudo sed -i "/^GRUB_CMDLINE_LINUX_DEFAULT=/ s/\"$*/${params}&/" "$file"
+
+    if _confirm "AMD GCN — GRUB" "Parameters added:\n\n  ${params}\n\nRun update-grub now?" 12 65; then
+        if sudo update-grub >/dev/null 2>&1; then
+            _msg "AMD GCN — Complete" "amdgpu parameters added to GRUB.\n\nBackup: ${backup}\n\nReboot to apply."
+        else
+            echo -e "${RED}update-grub failed. Restoring backup...${NC}"
+            sudo cp "$backup" "$file"
+            _msg "Error" "update-grub failed.\nBackup restored."
+        fi
+    else
+        _msg "AMD GCN" "Parameters written to ${file}.\nRun 'sudo update-grub' manually."
+    fi
+}
+
 _install_nvidia_stack() {
     if ! $HAS_NVIDIA; then
         _msg "NVIDIA Not Found" "No NVIDIA GPU was detected.\n\nPlease check your hardware and try again." 10 60