build(deps): converge on released workshop-rs 0.1.5

[Teakowa]

Summary

• bumps Wright's single canonical workshop-rs workspace dependency from =0.1.2 to =0.1.5;
• removes the temporary workshop-rs-provider git-pinned alias introduced for feat(wright): implement LanguageProvider for workshop-rs #193/test(wright): cross-validate check() output against workshop-rs P0 corpus #194 integration work;
• switches WorkshopProvider and P0 cross-validation imports back to the canonical workshop_rs crate so the workspace uses one crate instance.

Why

The git pin was only a development bridge while the provider/P0 owner contract from workshop-rs#74 was not yet available as a released crate. It should not ship in Wright 0.2.10.

Dependency / blocker

Blocked by wrightkit/workshop-rs#72 publishing workshop-rs 0.1.5 to crates.io. That release PR is currently open and green.

Cargo.lock is intentionally not fabricated before the crate is published: the crates.io checksum does not exist until publication. After 0.1.5 is published, regenerate the lockfile with Cargo, run the full Wright gates, and mark this PR ready.

This PR should land before the Wright 0.2.10 release PR #199.

Validation after workshop-rs 0.1.5 is published

• cargo update -p workshop-rs --precise 0.1.5
• cargo fmt --all -- --check
• cargo clippy --locked --workspace --all-targets --all-features -- -D warnings
• cargo test --locked --workspace --all-targets --all-features </dev/null
• cargo test --locked -p wright-driver --test workshop_provider -- --nocapture
• WRIGHTKIT_P0_ARTIFACT_DIR=<pinned-artifacts> cargo test --locked -p wright-driver --test p0_cross_validate -- --ignored --nocapture
• git diff --check

Non-goals

• no Workshop semantic changes;
• no provider-contract redesign;
• no wright-result/v1 changes;
• no unrelated dependency upgrades.