docs: remove stale scratch artifact files from repo root

[OTimileyin]

Closes #1093

Description

Remove four stale scratch/artifact files (ISSUE_134_SUMMARY.md, PR_DESCRIPTION.md, issue.md, pr.md) that were remnants of a past PR and not referenced by CI, scripts, or documentation anywhere in the codebase. Add .gitignore patterns to prevent similar scratch markdown files from being committed in the future.

Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📚 Documentation update
• 🔧 Refactoring (no functional changes)
• ⚡ Performance improvement
• 🧪 Test addition or update

Related Issues

Closes #1093

Changes Made

• Removed ISSUE_134_SUMMARY.md (209 lines)
• Removed PR_DESCRIPTION.md (85 lines)
• Removed issue.md (73 lines)
• Removed pr.md (34 lines)
• Updated .gitignore with scratch file patterns

Testing

Test Coverage

• Unit tests added/updated
• Integration tests added/updated
• Manual testing performed

Test Steps

1. Confirmed zero references to the four files across the entire repo (CI, scripts, docs, source)
2. Verified git status shows only the 5 allowed files were touched
3. Ran git diff main --stat to confirm changes are scoped correctly

Breaking Changes

None.

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published
• I have checked for breaking changes and documented them if applicable

Additional Notes

• pr_102_diff.txt is out of scope per the issue (tracked separately)