chore(project): quality improvements

[krokoko]

• add a failure in case of code coverage not being met (enforcing the rule)
• update the review pr command
• add new mise commands to run drift prevention mechanism as part of build

Area

• cdk — infrastructure, handlers, constructs
• agent — Python runtime / Docker image
• cli — bgagent client
• docs — guides or design sources (docs/guides/, docs/design/)
• tooling — root mise.toml, scripts, CI workflows

Tip: AGENTS.md lists where to edit and which tests to extend.

Related

Changes

Acknowledgment

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of the project license.

[isadeks]

Two things to fix before this can merge — otherwise the shape looks good.

1. Broken Starlight link in
   docs/src/content/docs/developer-guide/Contributing.md:61

The mirror points at /architecture/review-pr, which doesn't exist on the docs
site (no Review-pr.md under docs/src/content/docs/architecture/). The root
CONTRIBUTING.md:57 correctly uses a repo-relative path to
.abca/commands/review_pr.md, but that path doesn't translate to the published
site, so the mirror was hand-edited to a URL that goes nowhere.

Suggested fix: since .abca/commands/ isn't part of the published docs, link to
the GitHub source directly, or drop the link in the Starlight version and
keep the prose. Whichever you pick, please confirm mise //docs:sync
regenerates a consistent result (i.e. the source markdown's relative link is
what produces this absolute URL, not a manual edit).

2. agent/uv.lock revision downgraded 3 → 1

The header flipped from revision = 3 to revision = 1, and the 1425-line diff
is essentially stripping upload-time = "..." from every package entry — that's
the schema an older uv produces. Adding pytest-cov==7.1.0 alone should be a
~10-line diff. The next maintainer running uv sync with the project's pinned
uv will silently re-bump it to revision 3 and re-add all the metadata,
churning the lockfile again.

Suggested fix: regenerate the lockfile using the project-pinned uv (mise has
0.11.x available; looks like this was generated against an older Homebrew uv
0.9.9), then push only the actual pytest-cov addition.

Once those are addressed I'm happy to re-review. The contract → enforcement →
drift-check triad and the four-dimension heuristic in review_pr.md are well
done.