Fix duplicate packages in PR descriptions

[jdalton]

Removes duplicate package entries when same package appears multiple times in vulnerability data.

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Note

Deduplicates affected packages in PR descriptions and appends package ecosystem to package names in both single and multi-GHSA sections.

• PR body generation (src/commands/fix/git.mts):
  • Deduplicate **Affected Packages** lists using Set for single- and multi-GHSA bodies.
  • Include ecosystem alongside package name (e.g., name (ecosystem)) in listed packages across both paths.

^{Written by Cursor Bugbot for commit ff39f6c. Configure here.}