chore(dev): add pre-commit config mirroring the CI gates

[lfnovo]

From the repo quality assessment (CI/CD scored 53/100).

Status update (2026-07-12)

The CI half of this issue shipped in the v1.12.0 cleanup:

• ci: gate PRs on ruff, eslint and frontend build #1068 — PRs gated on ruff, eslint and the frontend build
• ci: gate PRs on mypy, start ignore_errors burn-down #1076 — PRs gated on mypy (with an ignore_errors burn-down started)

A PR that fails lint or type-check is now visibly red in CI. What remains is only the local pre-commit config.

Remaining scope

• Create .pre-commit-config.yaml wiring ruff (lint + format) and basic hygiene hooks (pre-commit is already in dev-deps); mirror what CI enforces so local commits fail for the same reasons PRs would.
• Document pre-commit install in docs/7-DEVELOPMENT/development-setup.md.

Acceptance criteria

• pre-commit install + a commit runs ruff locally.
• Hook config matches the CI gates (no "passes locally, fails in CI" drift for the covered tools).