fix: kidlisp bundler query parameter handling in module imports
- Strip query parameters from import paths before resolution (e.g., l5.mjs?v=...)
- Rewrite imports to preserve query params after path resolution
- Fix dependency discovery to correctly identify imports with cache-bust parameters
- Add lib/l5.mjs to ESSENTIAL_FILES (required by disk.mjs)
Fixes "Failed to resolve module specifier" errors when packing KidLisp pieces.
Query parameters like ?v=20260330-runtime-support were being treated as part of
the filename, breaking module resolution in packed .lisp.html files.
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>