fix(release): stamp Cargo.toml's version from the release tag

[kylehgc]

The first fork RC published as fork-dev-0.1.0-rc.9 and shipped:

rtk-0.42.4-1.x86_64.rpm
rtk_0.42.4-1_amd64.deb

Cargo.toml on develop carries whatever release-please last wrote on master, and nothing updates it for an RC. So rtk --version reports 0.42.4, telemetry records 0.42.4, and both packages are named for it.

Why this matters more for a fork

Upstream behaves identically — their dev-0.44.2-rc.344 ships the same rtk_0.42.4-1_amd64.deb filename. For them it's confusing. For us it's a collision: our artifact's name and version are byte-identical to upstream's own RC artifact, so two different binaries share one package identity. The fork- tag prefix exists precisely to prevent that, and the packages were left colliding.

Fix

CARGO_PKG_VERSION feeds --version, telemetry, cargo-deb, and cargo-generate-rpm. Stamping it once before each build fixes all four, rather than patching each consumer.

fork-dev-0.1.0-rc.9 → 0.1.0-rc.9, which is valid semver.

Verified

scripts/version-from-tag.sh --test    all 5 tag forms derive correctly
stamp diff                            line 3 only; clap = "4", serde = "1" untouched
cargo metadata                        rtk 0.1.0-rc.9  — cargo accepts the prerelease
grep --locked .github/workflows/      none, so the stale lockfile self-heals
Cargo.toml deb/rpm assets             not version-templated

Not verified locally: the resulting .deb/.rpm filenames — that needs cargo-deb on Linux. The next RC's published assets will show them, and that's the check worth watching after merge.

Classification

Original fix, not Fork Infrastructure — upstream has the same bug and can hold the fix. The Upstream PR is deferred by maintainer decision to avoid flooding upstream while the benchmark PR is in review. Recorded as owed in CONTEXT.md under "Deferred Upstream PRs" and tracked separately, so it does not silently become permanent divergence.

Deliberately not done

Renaming the package to rtk-fork. It would fix identity but break the drop-in-replacement property that is the fork's whole pitch — a visitor should install this instead of rtk, not alongside it.