feat(backend): add magpie-tts-cpp text-to-speech backend (#11115)

* feat(backend): add magpie-tts-cpp text-to-speech backend

Add a Go + purego backend wrapping the magpie-tts.cpp ggml port of NVIDIA's
Magpie TTS Multilingual 357M (encoder + autoregressive decoder over NanoCodec
tokens), producing 22.05 kHz mono audio in 5 baked voices (Aria, Jason, John,
Leo, Sofia; case-insensitive names or indices 0-4) across 9+ languages from a
single self-contained GGUF. Mirrors qwen3-tts-cpp / moss-tts-cpp: dlopen the
static-ggml shared library, bind the flat magpie_tts_capi_* C-API via purego
(no local C shim needed, the upstream .so exports it directly), and serve the
gRPC TTS + TTSStream methods behind base.SingleThread (the C context is not
reentrant across synthesize calls).

The backend CMakeLists translates the Makefile's -DGGML_{CUDA,METAL,VULKAN,HIP}
flags into upstream's MAGPIE_GGML_* toggles (upstream FORCE-overwrites the ggml
cache entries from those), pinned to magpie-tts.cpp v0.1.1
(e3f3dd1ebe22b64e7405f93b519f2d1930712568), which statically links ggml into
libmagpie-tts.so (ldd shows only system libs).

Wires the full registration: backend-matrix.yml (CPU amd64/arm64, CUDA 12/13,
Intel SYCL f16/f32, Vulkan amd64/arm64, ROCm, NVIDIA L4T + L4T CUDA 13, and
Darwin metal), backend/index.yaml metas and image entries, the root Makefile
build targets, the changed-backends backend-filter path mapping, the bump_deps
auto-bump matrix, a test-extra per-backend smoke job, the /backends/known
pref-only importer entry, the backend capabilities map (TTS + TTSStream, no
voice cloning), and the README / compatibility-table docs rows.

Verified locally: unit + e2e Ginkgo suites pass against the real q8_0 GGUF
(22.05 kHz mono WAV, RMS > 0.01), a live gRPC LoadModel + TTS round-trip
returns valid non-silent audio, and the pre-commit gates (make lint,
make test-coverage-check) pass, run manually with LOCALAI_TEST_HTTP_PORT
overriding the locally-occupied 9090.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* gallery: add magpie-tts-cpp model entries (q8_0 + f16)

Add the Magpie TTS Multilingual 357M GGUFs from mudler/magpie-tts.cpp-gguf to
the model gallery: q8_0 (~624 MB, near-lossless, fastest decode, recommended)
with an f16 (~784 MB) variant, both served by the magpie-tts-cpp backend.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* magpie-tts-cpp: bump pin to rewritten upstream v0.1.1 SHA

Upstream history was rewritten to purge accidentally committed build
artifacts; v0.1.1 now resolves to 6f7696cf.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Ettore Di Giacinto <mudler@localai.io>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

.github/workflows/bump_deps.yaml

@@ -110,6 +110,10 @@ jobs:
             variable: "VIBEVOICE_CPP_VERSION"
             branch: "master"
             file: "backend/go/vibevoice-cpp/Makefile"
+          - repository: "mudler/magpie-tts.cpp"
+            variable: "MAGPIETTS_CPP_VERSION"
+            branch: "main"
+            file: "backend/go/magpie-tts-cpp/Makefile"
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v7

.github/workflows/test-extra.yml

@@ -37,6 +37,7 @@ jobs:
       sglang: ${{ steps.detect.outputs.sglang }}
       acestep-cpp: ${{ steps.detect.outputs.acestep-cpp }}
       qwen3-tts-cpp: ${{ steps.detect.outputs.qwen3-tts-cpp }}
+      magpie-tts-cpp: ${{ steps.detect.outputs.magpie-tts-cpp }}
       rfdetr-cpp: ${{ steps.detect.outputs.rfdetr-cpp }}
       locate-anything-cpp: ${{ steps.detect.outputs.locate-anything-cpp }}
       vibevoice-cpp: ${{ steps.detect.outputs.vibevoice-cpp }}
@@ -866,6 +867,38 @@ jobs:
       - name: Test qwen3-tts-cpp
         run: |
           make --jobs=5 --output-sync=target -C backend/go/qwen3-tts-cpp test
+  tests-magpie-tts-cpp:
+    needs: detect-changes
+    if: needs.detect-changes.outputs.magpie-tts-cpp == 'true' || needs.detect-changes.outputs.run-all == 'true'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Clone
+        uses: actions/checkout@v7
+        with:
+          submodules: true
+      - name: Dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y build-essential cmake curl libopenblas-dev ffmpeg
+      - name: Setup Go
+        uses: actions/setup-go@v5
+      - name: Display Go version
+        run: go version
+      - name: Proto Dependencies
+        run: |
+          # Install protoc
+          curl -L -s https://github.com/protocolbuffers/protobuf/releases/download/v26.1/protoc-26.1-linux-x86_64.zip -o protoc.zip && \
+          unzip -j -d /usr/local/bin protoc.zip bin/protoc && \
+          rm protoc.zip
+          go install google.golang.org/protobuf/cmd/protoc-gen-go@v1.34.2
+          go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@1958fcbe2ca8bd93af633f11e97d44e567e945af
+          PATH="$PATH:$HOME/go/bin" make protogen-go
+      - name: Build magpie-tts-cpp
+        run: |
+          make --jobs=5 --output-sync=target -C backend/go/magpie-tts-cpp
+      - name: Test magpie-tts-cpp
+        run: |
+          make --jobs=5 --output-sync=target -C backend/go/magpie-tts-cpp test
   # Per-backend smoke for rfdetr-cpp: builds the .so + Go binary and runs
   # `make -C backend/go/rfdetr-cpp test`. test.sh fetches the small (~20 MB)
   # rfdetr-nano-q8_0 GGUF from the published mudler/rfdetr-cpp-nano HF repo