Route rg --files to find

[LK4D4]

Summary

• Rewrite simple rg --files hook invocations to RTK find syntax with explicit --max 50 and --file-type f.
• Preserve native behavior for unsupported shapes: pipes, extra flags, and multiple roots stay raw.
• Add regression coverage for simple roots, quoted paths, redirects, transparent prefixes, and conservative skip cases.

Why

rg --files is a common agent command for listing repository files. Right now, rtk rewrite rg --files returns rtk grep --files which doesn't work and only wastes execution.

I opted out for RTK syntax instead of find syntax to give hints to the agent about --max which works really bad with native syntax parser. We also should probably update rtk find --help to explain this stuff more.

Fix #2060