fix(turboquant): retain CPU variants in GPU builds (#11276)

Select the CPU_ALL_VARIANTS target for x86 GPU images so partial offload uses runtime-selected host kernels. Keep GPU arm64 builds on the portable fallback until their toolchains consistently provide gcc-14.

Assisted-by: Codex:gpt-5

Co-authored-by: localai-org-maint-bot <306269227+localai-org-maint-bot@users.noreply.github.com>

scripts/build/turboquant-build-target_test.sh

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+CURDIR=$(dirname "$(realpath "$0")")
+SELECTOR="$CURDIR/../../.docker/turboquant-build-target.sh"
+
+assert_target() {
+  local arch=$1
+  local build_type=$2
+  local expected=$3
+  local actual
+
+  actual=$("$SELECTOR" "$arch" "$build_type")
+  if [ "$actual" != "$expected" ]; then
+    echo "FAIL: $arch/$build_type selected $actual, expected $expected"
+    exit 1
+  fi
+}
+
+assert_target amd64 cublas turboquant-cpu-all
+assert_target amd64 vulkan turboquant-cpu-all
+assert_target amd64 "" turboquant-cpu-all
+assert_target arm64 cublas turboquant-fallback
+assert_target arm64 "" turboquant-cpu-all
+
+echo "PASS: turboquant build target preserves CPU variants where supported"