fix(contributors): correct YAML indentation in multiline strings

[CalvinAllen]

Summary

• Fixes YAML parse error introduced in fix(contributors): use table layout for HTML format to prevent vertical stacking #73 where multiline string lines had zero indentation inside the run: | block
• Lines inside YAML literal blocks must maintain the block's indentation level (10 spaces) for valid parsing — the YAML parser strips the leading whitespace, so bash receives the content at column 0

Test plan

• Manually trigger the contributors workflow on a repo using output-format: html (e.g., VS-MCPServer)
• Verify the workflow runs without YAML parse errors
• Verify contributor avatars render horizontally in the README