internal: Remove third-party plugins with dead locators

Verified every locator in registry/data/third-party.json: fetched all 114
https locators and resolved all 21 github:// locators via the GitHub API.

Removes 35 entries that can no longer be installed:

- 30 entries from Phault/proto-toml-plugins, as the entire repository no
  longer exists (all locators 404).
- 2 hugo entries, as the z0rrn/proto-plugins repository no longer exists.
- chester, as proto.toml was deleted from the repository.
- sdkman and terraform (ageha734), as those repositories have no releases,
  so the github:// locators have no wasm artifact to resolve.

Also repoints strawberry-perl from a github.com blob URL (which serves HTML,
not TOML) to the equivalent raw URL, as that plugin is still maintained.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: milesj