PyPI proxy improvements:
- Set package format to "pypi" instead of "generic"
- Extract version from filename and create PackageVersion record
- Support .whl, .tar.gz, and .zip filename formats
Package page UX overhaul:
- Move upload to header button with modal
- Simplify table: combine Tag/Version, remove Type and Artifact ID columns
- Add row action menu (⋯) with: Copy ID, Ensure File, Create Tag, Dependencies
- Remove cluttered "Download by Artifact ID" and "Create/Update Tag" sections
- Add modals for upload and create tag actions
- Cleaner, more scannable table layout
f3afdd3bbf