rust-toolchain.toml overrides `rustup default nightly`, so the scheduled
job ran cargo-fuzz on stable and its -Z flags failed (B7). Every cargo
call now names +nightly. Also:
- upload fuzz/artifacts/node/ when the run fails;
- drop the false claim that the corpus "grows in place across
schedules": new inputs live only in a 7-day artifact until someone
minimises and commits them;
- pin actions by SHA as ci.yml does (checkout v4.4.0, upload-artifact
v4.6.2), and install cargo-fuzz with --locked.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
kyleandClaude Opus 5.5