Delete textile/ERB infrastructure and test files

Remove all textile and ERB processing infrastructure code now that the
build pipeline no longer uses it. This includes workarounds, utilities,
and tests that validated textile parsing behavior.

Deleted:
- textile-js-workarounds directory (28 files)
- erbjs directory (ERB processing, 6 files + tests)
- Textile utility files and type definitions
- Test files dependent on textile/ERB processing

The build continues to work with no textile processing infrastructure.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: kennethkalmer