Asgard runner executes jobs in bare node:20-bullseye (no Rust, no sudo)
- install rustup + musl/mingw cross toolchains per-run, same pattern as
setup-go in the Go pipeline. agent-v2.0.0-alpha.1 predates this fix;
forward-only doctrine: version rolls to alpha.2 rather than re-pushing
the tag.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>