Add ARM64 (Apple Silicon) support for container builds

[claw-explorer]

Summary

• Fix hardcoded amd64 Anubis deb package URL to use ansible_architecture detection (same pattern already used for websocketd_filename)
• Enables native ARM64/aarch64 container builds on Apple Silicon Macs, AWS Graviton, and other ARM64 platforms

Changes

The anubis_deb_package URL in generic-dockerhub/vars.yml and generic-tarball/vars.yml was hardcoded to anubis_1.19.1_amd64.deb. This PR makes it architecture-aware:

# Before
anubis_deb_package: https://...anubis_1.19.1_amd64.deb

# After  
anubis_deb_package: "https://...anubis_1.19.1_{% if ansible_architecture == 'aarch64' %}arm64{% else %}amd64{% endif %}.deb"

This matches the existing pattern used for websocketd_filename on line 22 of the same files. Anubis provides official arm64 .deb packages, so no upstream changes are needed.

Motivation

The Evergreen ILS Docker image (mobiusoffice/evergreen-ils) is currently only available for linux/amd64. Running it on Apple Silicon requires QEMU emulation, which is significantly slower. With this fix, the image can be built natively on ARM64 — everything else in the Dockerfile and Ansible playbooks is already architecture-independent.

Testing

• Verified Anubis arm64 .deb exists at the generated URL
• Building natively on Apple Silicon M-series (macOS arm64 with podman)
• No changes to amd64 behavior (the Jinja2 conditional defaults to amd64)

Follow-up suggestion

Consider publishing multi-architecture images to Docker Hub using docker buildx or podman manifest so that mobiusoffice/evergreen-ils tags automatically serve the correct architecture. Happy to help with a CI workflow for this.

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