Adds an ubuntu-24.04-arm matrix entry so each release produces
mdcms-linux-arm64 and a matching arm64 .deb alongside the existing
amd64 artefacts. Fixes the fpm binary path and .deb artifact name to
be matrix-driven so both Linux builds are independent.
https://claude.ai/code/session_01LScjwzJJgLKsNrqEPLxJS8
Triggered on version tags (v*). Builds standalone binaries via PyInstaller
on Linux/macOS/Windows runners, wraps the Linux binary in a .deb via fpm,
and attaches all artifacts to a GitHub release.
https://claude.ai/code/session_01MqEqGhP1guGx5VuFsLaws2