feat(backends): add CachyLLaMA support

Add CachyLLaMA as a GGUF-compatible llama.cpp fork backend with CPU and Vulkan builds on Linux and Metal on Apple silicon. Expose it through model import, document persistent SSD cache options, and wire CI path filtering and dependency updates.

Assisted-by: Codex:gpt-5

.github/workflows/backend_build_darwin.yml

@@ -230,6 +230,12 @@ jobs:
           make protogen-go
           make backends/llama-cpp-darwin
 
+      - name: Build CachyLLaMA backend (Darwin Metal)
+        if: inputs.backend == 'cachyllama'
+        run: |
+          make protogen-go
+          make backends/cachyllama-darwin
+
       - name: Build ds4 backend (Darwin Metal)
         if: inputs.backend == 'ds4'
         run: |
@@ -256,7 +262,7 @@ jobs:
           make backends/audio-cpp-darwin
 
       - name: Build ${{ inputs.backend }}-darwin
-        if: inputs.backend != 'llama-cpp' && inputs.backend != 'ds4' && inputs.backend != 'privacy-filter' && inputs.backend != 'audio-cpp'
+        if: inputs.backend != 'llama-cpp' && inputs.backend != 'cachyllama' && inputs.backend != 'ds4' && inputs.backend != 'privacy-filter' && inputs.backend != 'audio-cpp'
         run: |
           make protogen-go
           BACKEND=${{ inputs.backend }} BUILD_TYPE=${{ inputs.build-type }} USE_PIP=${{ inputs.use-pip }} make build-darwin-${{ inputs.lang }}-backend

.github/workflows/bump_deps.yaml

@@ -22,6 +22,10 @@ jobs:
             variable: "TURBOQUANT_VERSION"
             branch: "feature/turboquant-kv-cache"
             file: "backend/cpp/turboquant/Makefile"
+          - repository: "fewtarius/CachyLLama"
+            variable: "CACHYLLAMA_VERSION"
+            branch: "master"
+            file: "backend/cpp/cachyllama/Makefile"
           - repository: "PrismML-Eng/llama.cpp"
             variable: "BONSAI_VERSION"
             branch: "prism"