Transparency Log Improvements

A few improvements I'd like to see on the transparency log:

- [ ] Ability to deep link to a specific entry to easily share it with someone else
- [ ] version created/changed events shouldn't just show the commit hash but also the date, so you can see a version created in 2026 is actually from a git tag created with a (potentially fake) date a year ago.
- [ ] package pages should link to the transparency log filtered by their package name to simplify looking this up. => #1766

Start by locating the transparency log entry points and the package page views, then trace how entries are identified, how version events are rendered, and how package links are built. Confirm whether the package-filtering request belongs in issue #1766; done means the remaining requested transparency-log improvements are implemented and their behavior is covered by the relevant tests.

Written by the indexing model from the issue text.