build(arm64): cross-compile parakeet-cli for the Raspberry Pi 5

[richiejp]

Static, self-contained aarch64 build via docker buildx + qemu, mirroring the
privacy-filter.cpp approach. Base ubuntu:24.04 matches the Pi 5's glibc 2.39 ABI
so the binary drops straight on; it targets the Cortex-A76
(armv8.2-a+dotprod+fp16) and links only the system libc/libstdc++/libgomp (ggml
and libparakeet are static).

docker buildx build --platform linux/arm64 -f docker/Dockerfile.arm64
--target export --output type=local,dest=build/arm64 .

The build context drops .git (.dockerignore), which dangles the ggml submodule's
gitlink and breaks scripts/apply_ggml_patches.sh (it uses git apply). Re-init a
throwaway git repo in the submodule tree before configure so the in-tree ggml
patches (the sgemm broadcast-fold, etc.) apply -- worth ~9% at 4 threads on the Pi.

Co-Authored-By: Claude Opus 4.8 (1M context) noreply@anthropic.com

[mudler]

@richiejp can we hook up to the CI images so it gets published?

[richiejp]

I guess there are two ways to go about this, one is to publish a docker image, which I'm not sure it makes sense for Rpi or do true static compilation including libc and OpenMP. The later makes most sense to me if it is possible. I'll give it a shot