Add pre-commit setup

[Copilot]

Adds pre-commit configuration and GitHub Actions workflow, copied from canonical/mir repository.

Changes

• .pre-commit-config.yaml - Hooks for trailing whitespace, end-of-file fixing, large file detection, mdformat, and pymarkdown
• .pymarkdown.json - Markdown linting rules adapted from mir's configuration
• .github/workflows/pre-commit.yaml - Workflow runs on PRs and main branch pushes, auto-applies fixes via pre-commit-ci/lite-action

Configuration

Pre-commit hooks automatically applied formatting fixes to existing files (trailing whitespace and EOF normalization). The workflow uses explicit contents: write permissions per security requirements.

The pymarkdown config path was adapted from mir's doc/sphinx/.sphinx/.pymarkdown.json to .pymarkdown.json in root, as wlcs lacks the sphinx directory structure.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Add pre-commit setup</issue_title>
<issue_description>@Saviq Maybe we should have precommit here too?

Originally posted by @tarek-y-ismail in #387 (review)
</issue_description>

<agent_instructions>Copy the pre-commit config and github action from https://github.com/canonical/mir/</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Add pre-commit setup #388

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✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[Saviq]

Yup.

[Saviq]

@copilot please rebase

[Copilot]

@copilot please rebase

I've successfully rebased the branch onto the latest main (83abb18). The rebase resolved conflicts where the spread build task files were deleted in main but had whitespace fixes in my changes.

However, I cannot force-push the rebased branch due to system restrictions. The rebased commits are ready locally:

• ad65dac Initial plan
• 9d3e289 Add pre-commit configuration and GitHub Actions workflow
• 7de5932 Add explicit permissions to pre-commit workflow for security

Could you please force-push the branch, or grant permission for me to do so?

[github-actions]

TICS Quality Gate

✔️ Passed

wlcs

Coding Standards: ✔️ Passed

✔️ Condition “No new Coding Standard Violations for level 1, 2, 3 with respect to Previous analysis” passed.

See the results in the TICS Viewer

The following files have been checked for this project

• src/main.cpp

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