[dependabot]

• Closes https://github.com/ComPWA/.github-private/issues/23
• Closes https://github.com/ComPWA/.github-private/issues/28
• Closes https://github.com/ComPWA/.github-private/issues/35

🖱️ Developer experience

• linkcheck runs lychee over all repository sources instead of the Sphinx linkcheck builder, so it also checks notebooks, workflows and configuration files and verifies anchors.
• Pull requests now request a review from @ComPWA/maintainers automatically through a new CODEOWNERS file.
• Documentation can use GitHub-style alerts such as > [!TIP], which also render on GitHub, through the MyST alert extension (myst-parser>=5.1).

🔨 Maintenance

• Read the Docs installs the doc dependency group with its native uv support instead of a custom Pixi install script, and fails the build on Sphinx warnings.
• The 75% coverage threshold is set once through fail_under in the coverage configuration instead of in the pytest arguments and codecov.yml.
• Docstrings are formatted with docstrfmt.

Squash commit messages

* DX: request reviews from code owners
* DX: support GitHub-style alerts in the documentation
* MAINT: build Read the Docs with its native uv support
* MAINT: define coverage threshold in coverage configuration
* MAINT: format docstrings with docstrfmt