feat(paged): restrict llama-cpp-localai-paged to CUDA-only build targets

The paged backend previously built for cublas/cuda, cpu, vulkan, sycl,
hipblas and darwin/metal. On non-CUDA the patchset's wins are inert: the
GDN fusions are gated off (patch 0030) and NVFP4 falls back to dequant,
so the backend is neutral-to-negative there (README section 4c). The
darwin grpc-server link also fails on undefined upstream server symbols,
turning CI red. Both broken and pointless off-CUDA, so ship CUDA-only.

- backend-matrix.yml: drop the hipblas, sycl f32/f16, cpu amd64/arm64,
  vulkan amd64/arm64 and metal-darwin rows for this backend; keep the
  four cublas rows (cuda-12, cuda-13, nvidia-l4t cuda-12 and cuda-13).
- index.yaml: meta-backend (and -development) capabilities are now
  CUDA-only with default pointing at cuda12 (mirrors faster-qwen3-tts);
  removed the orphaned cpu/rocm/sycl/vulkan/metal variant entries.
- Removed the now-unused darwin build script and its Makefile target /
  .NOTPARALLEL entry / backend_build_darwin.yml step.
- Documented the CUDA-only build coverage in the patch README and plan.

Non-CUDA users should use the stock llama-cpp backend.

Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

scripts/build/llama-cpp-localai-paged-darwin.sh

@@ -1,95 +0,0 @@
-#!/bin/bash
-
-set -ex
-
-# Darwin/Metal build for the llama-cpp-localai-paged backend. Mirrors
-# scripts/build/llama-cpp-darwin.sh exactly, swapping the build dir, binary names,
-# shared-lib dir and output tar for the paged wrapper. The paged wrapper Makefile
-# (backend/cpp/llama-cpp-localai-paged) reuses backend/cpp/llama-cpp's CMakeLists
-# /grpc-server and applies its own vendored paged patch series (patches/paged/)
-# onto the cloned tree, so the Darwin/Metal path is identical: ggml
-# CPU_ALL_VARIANTS + GGML_METAL=ON, and --target ggml pulls in ggml-metal via
-# add_dependencies so the Metal GPU backend is produced as a loadable
-# libggml-metal.dylib. The new paged GDN/conv ops have no Metal kernel, so a
-# gated-DeltaNet (qwen35) model falls back to the CPU reference op at runtime
-# (assert/fall-back is made SAFE by the fused-op backend gate, patch 0030); a
-# non-qwen35 model gets the full paged-KV path on Metal.
-
-IMAGE_NAME="${IMAGE_NAME:-localai/llama-cpp-localai-paged-darwin}"
-
-pushd backend/cpp/llama-cpp-localai-paged
-
-# Single build via ggml CPU_ALL_VARIANTS: one binary plus the per-microarch Apple/arm
-# dylibs (apple_m1/m2_m3/m4, armv8.x) that ggml selects at runtime. GGML_METAL stays ON
-# and --target ggml also builds ggml-metal (via add_dependencies), so the Metal GPU
-# backend is still produced as a loadable libggml-metal.dylib.
-make llama-cpp-localai-paged-cpu-all && \
-make llama-cpp-localai-paged-grpc && \
-make llama-cpp-localai-paged-rpc-server
-
-popd
-
-mkdir -p build/darwin
-mkdir -p backend-images
-mkdir -p build/darwin/lib
-
-cp -rf backend/cpp/llama-cpp-localai-paged/llama-cpp-localai-paged-cpu-all build/darwin/
-cp -rf backend/cpp/llama-cpp-localai-paged/llama-cpp-localai-paged-grpc build/darwin/
-cp -rf backend/cpp/llama-cpp-localai-paged/llama-cpp-localai-paged-rpc-server build/darwin/
-
-# Distribute the shared ggml/llama libraries from the CPU_ALL_VARIANTS build. Unlike the
-# old fully-static fallback build, these have @rpath install names, so the otool loop below
-# (which only copies deps that exist on disk) will not pick them up. The split is by suffix:
-#  - ggml emits its loadable backends (per-microarch CPU variants, metal, blas) with a .so
-#    suffix EVEN ON DARWIN. These go in the package ROOT next to the binary, because darwin
-#    run.sh execs the binary directly (no bundled ld.so) so ggml's executable-directory
-#    scan looks there.
-#  - the core libraries (libggml-base/libggml/libllama/libllama-common/libmtmd) use the
-#    platform .dylib suffix and are NEEDED deps; they go in lib/, resolved at load time via
-#    the DYLD_LIBRARY_PATH=lib that run.sh exports. -a preserves the version symlinks.
-SHLIBS=backend/cpp/llama-cpp-localai-paged/ggml-shared-libs
-cp -a $SHLIBS/*.so build/darwin/
-cp -a $SHLIBS/*.dylib build/darwin/lib/
-
-# Set default additional libs only for Darwin on M chips (arm64)
-if [[ "$(uname -s)" == "Darwin" && "$(uname -m)" == "arm64" ]]; then
-    ADDITIONAL_LIBS=${ADDITIONAL_LIBS:-$(ls /opt/homebrew/Cellar/protobuf/**/lib/libutf8_validity*.dylib 2>/dev/null)}
-else
-    ADDITIONAL_LIBS=${ADDITIONAL_LIBS:-""}
-fi
-
-for file in $ADDITIONAL_LIBS; do
-  cp -rfv $file build/darwin/lib
-done
-
-for file in build/darwin/*; do
-  LIBS="$(otool -L $file | awk 'NR > 1 { system("echo " $1) } ' | xargs echo)"
-  for lib in $LIBS; do
-    # only libraries ending in dylib
-    if [[ "$lib" == *.dylib ]]; then
-        if [ -e "$lib" ]; then
-            cp -rvf "$lib" build/darwin/lib
-        fi
-    fi
-  done
-done
-
-echo "--------------------------------"
-echo "ADDITIONAL_LIBS: $ADDITIONAL_LIBS"
-echo "--------------------------------"
-
-echo "Bundled libraries:"
-ls -la build/darwin/lib
-
-
-cp -rf backend/cpp/llama-cpp-localai-paged/run.sh build/darwin/
-
-PLATFORMARCH="${PLATFORMARCH:-darwin/arm64}"
-
-./local-ai util create-oci-image \
-        build/darwin/. \
-        --output ./backend-images/llama-cpp-localai-paged.tar \
-        --image-name $IMAGE_NAME \
-        --platform $PLATFORMARCH
-
-rm -rf build/darwin