Improve Renovate config

[AlexWaygood]

Followup to #792.

• Replace the single CI dependencies group with:
  • pre-commit dependencies for .pre-commit-config.yaml, including hook revisions and additional dependencies.
  • GitHub Actions dependencies for .github/workflows/**, including action references and the custom uv/Codecov tool pins.
  • Build dependencies for the managed PEP 621 build requirements.
• Add config:recommended, replacements:all, and abandonments:recommended to the presets we extend.
• Extend abandonments:recommended to report packages with no release for a year, subject to Renovate's curated package-specific exceptions.
• Enable configMigration so Renovate can propose configuration migrations when its configuration format changes.
• Set separateMajorMinor: false so major and non-major updates can share the same dependency group.
• Set prHourlyLimit and prConcurrentLimit to 0, removing the default limits of two new PRs per hour and ten open PRs so they do not constrain the monthly update window.
• Set semanticCommits: "disabled". We don't use semantic commit titles in this repo.
• Suppress prEditedNotification, the comment explaining that Renovate has stopped automatically rebasing a manually edited branch. These notifications are noisy and annoying.

Many/most of these config options are ones we've been using in Astral repos for a while, and they've served us well over there. I validated the changes using npx --yes --package renovate@43.280.2 -- renovate-config-validator --strict --no-global .github/renovate.json5.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.26%. Comparing base (d146ae8) to head (11a866e).

@@           Coverage Diff           @@
##             main     #794   +/-   ##
=======================================
  Coverage   97.26%   97.26%           
=======================================
  Files           3        3           
  Lines        7859     7859           
=======================================
  Hits         7644     7644           
  Misses        215      215           

Flag	Coverage Δ
3.10	88.85% <ø> (ø)
3.10.4	88.85% <ø> (ø)
3.11	88.02% <ø> (ø)
3.11.0	87.27% <ø> (ø)
3.12	87.96% <ø> (ø)
3.12.0	87.94% <ø> (ø)
3.13	83.39% <ø> (ø)
3.13.0	84.09% <ø> (ø)
3.14	79.53% <ø> (ø)
3.9	89.53% <ø> (ø)
3.9.12	89.53% <ø> (ø)
pypy3.10	88.68% <ø> (ø)
pypy3.11	87.88% <ø> (ø)
pypy3.9	89.37% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.