chore: extend pre-commit with hygiene hooks, prettier, and .prettierignore

[clappingmonkey]

What does this PR do?

Extends the pre-commit configuration with standard file hygiene hooks and Prettier formatting for Markdown/YAML files.

New hooks

pre-commit/pre-commit-hooks v6.0.0:

• trailing-whitespace — strips trailing whitespace
• end-of-file-fixer — ensures files end with newline
• check-yaml — validates YAML syntax
• check-merge-conflict — detects conflict markers
• check-added-large-files — prevents >500KB commits
• check-case-conflict — prevents case-insensitive filename clashes

rbubley/mirrors-prettier v3.9.4 (active fork — pre-commit/mirrors-prettier archived 2024):

• prettier hook scoped to types_or: [markdown, yaml]
• No .prettierrc needed — prettier defaults are fine (bazel-contrib convention)

New files

• .prettierignore — excludes Bazel files, generated/cache, Odin source, plain text, and personal files from prettier

Auto-fixed files (formatting only, no semantic changes)

• README.md — table column alignment
• COMPATIBILITY.md — table column alignment
• .github/workflows/scorecard.yaml — removed extra spaces before inline comment

Hook ordering

1. File hygiene (trailing-whitespace, end-of-file, check-yaml, etc.)
2. Buildifier (Starlark formatting + lint)
3. Typos (spell check)
4. Prettier (Markdown + YAML formatting)

How was it tested?

• .venv/bin/pre-commit run --all-files — all 10 hooks pass
• bazel build //... in root workspace — passes
• cd e2e/smoke && bazel build //... — passes
• Adversarial review by @change-validator — APPROVE, no issues found

Checklist

• PR title follows conventional commit format
• CI passes (check.yaml — lint + test matrix)
• No tests needed (configuration + formatting only)
• No breaking changes