fix(ci): sync mise lock header with CI

[drew]

Summary

Normalize mise.lock to the output generated by the pinned CI mise version so branches based on main pass the existing exact lockfile check.

Related Issue

N/A

Changes

• Update the generated mise.lock header from mise.jdx.dev to mise.en.dev, matching mise lock from the pinned CI mise version.
• Document that the mise-lockfile job intentionally enforces exact lockfile equality, including generated metadata, so mise version drift is visible.

Testing

• mise run pre-commit passes
• mise lock with network access
• git diff --exit-code mise.lock passes after regeneration
• git diff --check passes
• mise run python:proto passes after the initial pre-commit failure

Note: mise run pre-commit failed because python:proto ran before uv finished recreating .venv, producing ModuleNotFoundError: No module named grpc_tools. Rerunning the failed task after dependency setup passed.

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)
• Architecture docs updated (if applicable)