feat(backend): add moss-transcribe-cpp backend (MOSS-Transcribe-Diarize) (#10756)

C++/ggml transcription + speaker diarization + timestamps backend. Purego
dlopens libmoss-transcribe.so (ggml statically linked) from moss-transcribe.cpp
and serves offline AudioTranscription, parsing the [start][Sxx]text[end] output
into segments with nanosecond timestamps. Adds the importer (surfaces in
GET /backends/known), backend-matrix (Linux + Darwin/metal), backend/index.yaml,
and a gallery entry (default q5_k GGUF from mudler/moss-transcribe.cpp-gguf).

Local L0 smoke (go build + go test ./... = 16 pass, golangci-lint 0 issues)
passed against the real libmoss-transcribe.so. The pre-commit coverage gate
(full pkg/core + tests/e2e) could not run in the authoring sandbox (no live
models, port 9090 held); CI must enforce it before merge.

Assisted-by: Claude:claude-opus-4-8 golangci-lint

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Co-authored-by: Ettore Di Giacinto <mudler@localai.io>

.github/workflows/bump_deps.yaml

@@ -42,6 +42,10 @@ jobs:
             variable: "PARAKEET_VERSION"
             branch: "master"
             file: "backend/go/parakeet-cpp/Makefile"
+          - repository: "mudler/moss-transcribe.cpp"
+            variable: "MOSS_VERSION"
+            branch: "master"
+            file: "backend/go/moss-transcribe-cpp/Makefile"
           - repository: "mudler/ced.cpp"
             variable: "CED_VERSION"
             branch: "master"