fix(release): preserve version across jobs

[Teakowa]

Summary

Fix the release workflow regression where downstream jobs received an empty release version.

Root cause

The workflow referenced job outputs as needs.prepare.version / needs.prepare.commit. GitHub Actions job outputs must be accessed through needs.<job>.outputs.<name>. During the current v0.1.1 release this produced unversioned artifacts such as workshop-rs-cli--x86_64-unknown-linux-gnu.tar.gz and left VERSION empty in the crates.io publish job.

Changes

• Make build/publish/release jobs depend directly on the plan job for the authoritative release version.
• Use needs.prepare.outputs.commit for the prepared release revision.
• Add fail-fast guards so empty versions cannot create artifacts, publish crates, or assemble a GitHub Release.
• Preserve the existing v0.1.1 resume/idempotency behavior; this does not create or bump another release version.

Validation

• Compared against current main; only .github/workflows/release.yml changes.
• Current release logs prove plan.version=0.1.1 reaches prepare, while the old downstream needs.prepare.version expression evaluates empty.
• Downloaded release artifact confirms the regression: workshop-rs-cli--x86_64-unknown-linux-gnu.tar.gz.

The crates.io verified-email failure is separate and intentionally out of scope.