feat(parakeet-cpp): L3 register backend in build/CI/gallery (whisper parity)

Wire the new Go gRPC parakeet-cpp backend (parakeet.cpp ggml port of NVIDIA
NeMo Parakeet ASR) into LocalAI's build/CI/gallery surfaces, matching the
existing ggml whisper Go backend 1:1.

- .github/backend-matrix.yml: add 11 linux entries + 1 darwin entry mirroring
  every whisper build (cpu amd64/arm64, intel sycl f32/f16, vulkan amd64/arm64,
  nvidia cuda-12, nvidia cuda-13, nvidia-l4t-arm64, nvidia-l4t-cuda-13-arm64,
  rocm hipblas, metal-darwin-arm64), all on ./backend/Dockerfile.golang with
  backend: "parakeet-cpp" and -*-parakeet-cpp tag-suffixes.
- scripts/changed-backends.js: explicit inferBackendPath branch resolving
  parakeet-cpp to backend/go/parakeet-cpp/ before the generic golang branch.
- .github/workflows/bump_deps.yaml: track the PARAKEET_VERSION pin in
  backend/go/parakeet-cpp/Makefile (repo mudler/parakeet.cpp, branch master).
- backend/index.yaml: add &parakeetcpp meta + latest/development image entries
  for every matrix tag-suffix.
- Makefile: add backends/parakeet-cpp to .NOTPARALLEL, BACKEND_PARAKEET_CPP
  definition, docker-build target eval, and test-extra-backend-parakeet-cpp-
  transcription target (mirrors test-extra-backend-whisper-transcription).

Assisted-by: Claude:claude-opus-4-8 [Claude Code]

scripts/changed-backends.js

@@ -18,6 +18,14 @@ function inferBackendPath(item) {
   if (item.dockerfile.endsWith("python")) {
     return `backend/python/${item.backend}/`;
   }
+  // parakeet-cpp is a Go backend (Dockerfile.golang) wrapping the parakeet.cpp
+  // ggml port via purego. It lives in backend/go/parakeet-cpp/; this explicit
+  // branch (placed before the generic golang one, which would also resolve it
+  // correctly) documents the mapping and guards against a future
+  // dockerfile-suffix change.
+  if (item.backend === "parakeet-cpp") {
+    return `backend/go/parakeet-cpp/`;
+  }
   if (item.dockerfile.endsWith("golang")) {
     return `backend/go/${item.backend}/`;
   }