Add a feature where each package gets a page at /-/packages/name-of-package which is a page that shows the available metadata about that package, including the README - rendered as plain text using pre-wrap styling

The /-/packages page should stop showing JSON and should instead show an HTML. list of those packages, each a link to that page, still also showing the version number

Summary

This PR enhances the datasette-packages plugin by adding individual package detail pages and improving the overall user interface with proper HTML templates instead of generic JSON rendering.

Key Changes

• New package detail route: Added /-/packages/<package_name> endpoint that displays detailed metadata and README for individual packages
• Improved packages list: Changed the packages listing from displaying raw JSON to a user-friendly HTML page with clickable links to package details
• Custom templates: Created two new HTML templates (packages_list.html and package_detail.html) that extend the base Datasette template
• Template directory registration: Added extra_template_dirs() hook implementation to register the templates directory
• Data structure refactor: Changed internal package representation from dict to list of dicts to better support template rendering
• Package metadata handling: Implemented proper extraction and display of package metadata including support for multi-value fields
• README support: Added extraction and display of package README content from metadata
• Error handling: Added 404 response for non-existent packages
• Setup configuration: Updated setup.py to include template files in package distribution

Notable Implementation Details

• Package metadata is extracted using dist.metadata.get_all() to properly handle fields that can have multiple values
• The JSON endpoint maintains backward compatibility by converting the list back to a dict format
• README content is extracted via dist.metadata.get_payload() and only displayed if non-empty
• Tests have been updated to verify the new HTML output and added comprehensive tests for the detail page functionality

https://claude.ai/code/session_01NweDU9Kg1no11mAq3azT55