nvidia menu & management updates

- Refined `_show_nvidia_version_menu` in `modules/gpu/nvidia.sh` for Debian 12/13 with precise labels ("Newest Stable", "Kepler Support") and explicit official repo recommendations.
- Introduced new standalone module `modules/gpu/nvidia_manage.sh` integrated into the dispatcher to handle driver lifecycle management (Install/Change vs Remove) before version selection.
- Implemented safe removal logic (`_nvidia_remove`) with explicit package purging, explicitly excluding `firmware-misc-nonfree`, and cleaning specific configs/repos without wildcards.
- Ensured idempotency across all steps using `|| true` and preserved user CUDA toolkits while restoring Nouveau via initramfs regeneration.

modules/gpu.sh

@@ -5,6 +5,7 @@ _GPU_DIR="${MODULES_DIR}/gpu"
 source "${_GPU_DIR}/_helpers.sh"
 source "${_GPU_DIR}/amd_intel.sh"
 source "${_GPU_DIR}/nvidia.sh"
+source "${_GPU_DIR}/nvidia_manage.sh"
 
 # Consumed by gaming.sh to know which NVIDIA driver path was taken
 NVIDIA_DRIVER_MODE=""
@@ -193,6 +194,10 @@ _install_nvidia_stack() {
 
     NVIDIA_DRIVER_MODE=""
 
+    if ! _nvidia_manage_menu; then
+        return
+    fi
+
     if [ "$DEBIAN_VERSION" = "11" ]; then
         install_nvidia_bullseye