Merges Yarn v1 and Yarn Berry (v2+) migration into ONE yarn.zig file.
Changes:
- Auto-detects v1 vs Berry at runtime
- Shared workspace scanning and package.json parsing
- Full Berry metadata support:
✅ bin definitions (single/named/map formats)
✅ peerDependencies (added with .peer behavior)
✅ dependenciesMeta (optional markers)
✅ checksum conversion (Berry format → Bun integrity)
Deleted files:
- yarn_berry.zig (merged into yarn.zig)
- yarn_common.zig (merged into yarn.zig)
Missing from Berry (Bun will fetch from npm registry):
- scripts (not in lockfile)
- os/cpu constraints (not commonly in Berry lockfiles)
- man pages
Test status:
- v1 tests: ✅ passing
- Berry tests: need fixtures with proper YAML format
