build: lint TOML with Tombi

[iloveitaly]

Motivation

TOML in this repo had no formatter or linter. Taplo is not maintained, so the check uses Tombi, which is actively released and covers format, lint, and schema checks.

Description

• Install Tombi through mise (tombi = "latest", locked to 1.5.5 by the 14-day release-age setting) in .config/mise.dev.toml.
• Add just toml_lint and just toml_lint_fix, and include them in just lint and just fix.
• Run the check on pre-push and in the backend CI job.
• Recommend the Tombi VS Code extension and use it as the TOML formatter.
• Skip every **/*.lock file, plus vendored metadata under .config/mise/locks/. Leave pyproject.toml in its existing key order so uv add is not rewritten.

Screenshots / Test

just toml_lint on the repo:

12 files did not need formatting
12 files linted successfully

tombi format --check exits 1 on an unformatted file ("pytest.toml" is not formatted) and exits 0 after the file is restored.

A deliberately unformatted web/mise.lock is ignored by tombi format --check because of the **/*.lock exclude.

Links

• https://github.com/tombi-toml/tombi
• https://tombi-toml.github.io/tombi/docs/configuration/