chore: stop tracking docs and ignore local .codex

[GatewayJ]

Type of Change

• New Feature
• Bug Fix
• Documentation
• Performance Improvement
• Test/CI
• Refactor
• Other: repository housekeeping (git tracking scope)

Related Issues

N/A

Summary of Changes

• Added docs/ and .codex/ to .gitignore.
• Removed tracked docs/* files from Git index via cached removal, while keeping local files on disk.
• Kept change scope limited to index/ignore behavior (no runtime/operator logic changes).

Checklist

• I have read and followed the CONTRIBUTING.md guidelines
• Passed make pre-commit (fmt-check + clippy + test + console-lint + console-fmt-check)
• Added/updated necessary tests
• Documentation updated (if needed)
• CHANGELOG.md updated under [Unreleased] (if user-visible change)
• CI/CD passed (if applicable)

Impact

• Breaking change (CRD/API compatibility)
• Requires doc/config/deployment update
• Other impact:

Verification

# confirm tracked removals + ignore rules
git status --short

git check-ignore -v docs .codex

Additional Notes

• This PR intentionally changes repository tracking only.
• Local docs/ files are preserved in working tree; only Git index tracking is removed.

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