Track shared release workflow from main

[Teakowa]

Goal

Make WrightKit crate consumers follow the shared release workflow directly from wrightkit/.github@main so routine shared-workflow maintenance does not require synchronized consumer pin updates.

Context

The shared release workflow is an internal WrightKit CI contract. Immutable consumer SHAs add operational coupling: every squash merge in wrightkit/.github requires follow-up PRs in each consumer, and using a pre-merge PR head SHA can leave consumers pointing at a non-durable revision.

External release tooling remains pinned inside the shared workflow; this change only removes immutable pinning between WrightKit-owned repositories.

Scope

• Change current consumers of .github/workflows/release-plz-crates.yml to reference @main.
• Apply the policy consistently to opy-rs, workshop-rs, and deltin-rs.
• Keep consumer permissions, secrets, triggers, and release-plz policy unchanged.
• Keep external Action and release-plz CLI version pinning owned by wrightkit/.github.

Non-goals

• Change release versioning, changelog, or publication policy.
• Change the shared workflow implementation.
• Add release automation to repositories that do not currently consume it.

Acceptance criteria

• opy-rs, workshop-rs, and deltin-rs use wrightkit/.github/.github/workflows/release-plz-crates.yml@main.
• Consumer release workflows otherwise remain unchanged.
• A post-merge release run resolves the shared workflow from wrightkit/.github main and creates the expected release/release-pr jobs.
• Already-published packages remain a safe no-op.

[Teakowa]

Implemented and verified.

Consumers now track the shared release workflow from @main:

• ci(release): track shared workflow from main opy-rs#123
• ci(release): track shared workflow from main workshop-rs#134
• ci(release): track shared workflow from main deltin-rs#82

Post-merge evidence:

• opy-rs Release-plz run 33327748532 resolved wrightkit/.github/.github/workflows/release-plz-crates.yml@main to the current .github/main revision and both release jobs succeeded.
• workshop-rs Release-plz run 33327795754 resolved @main and both release jobs succeeded.
• deltin-rs Release-plz run 33327800805 resolved @main and both release jobs succeeded.

Current main in all three consumers now references release-plz-crates.yml@main. External release-plz Action/CLI pinning remains owned by the shared workflow.