fix: preserve stable v1 schema identifiers

[ovaso]

Summary

• restore the original v1 JSON Schema $id values as stable protocol identifiers
• clarify that the legacy namespace is intentional and is not a repository download URL
• synchronize bilingual automation contracts, the repository-local skill, black-box coverage, and v0.4.5 changelogs

Validation

• cargo fmt -- --check
• cargo test --locked
• cargo clippy --all-targets --all-features -- -D warnings
• cargo build --locked --release
• release binary reports both original v1 schema identifiers

Risk and rollback

This restores the pre-move identifiers and prevents a compatibility break for schema caches and allowlists. Repository, installer, release, badge, and attestation URLs remain pointed at ovaso/batch-git-rs.