build: replace uniq with sort -u to deduplicate directories in CI workflows

[Planeshifter]

Resolves stdlib-js/metr-issue-tracker#1113.

Description

What is the purpose of this pull request?

This pull request:

• Replaces uniq with sort -u in all CI workflow YAML files and their companion shell scripts to properly deduplicate directory lists.
• Adds a deduplication step after merging changed directories with dependent directories in the affected tests script.

The uniq command only removes adjacent duplicates, so when git diff output produces the same parent directory in non-adjacent positions (e.g., files in root interleaved with subdirectory files), duplicate directory entries survive. This causes test files, benchmarks, and coverage runs to execute multiple times for the same package. For example, in this run, every test file for @stdlib/complex/float32/base/div ran twice.

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

• Prevent tests from running twice in run_affected_tests workflow metr-issue-tracker#1113

Questions

Any questions for reviewers of this pull request?

No.

Other

Any other information relevant to this pull request? This may include screenshots, references, and/or implementation notes.

No.

Checklist

Please ensure the following tasks are completed before submitting this pull request.

• Read, understood, and followed the contributing guidelines.

AI Assistance

When authoring the changes proposed in this PR, did you use any kind of AI assistance?

• Yes
• No

If you answered "yes" above, how did you use AI assistance?

• Code generation (e.g., when writing an implementation or fixing a bug)
• Test/benchmark generation
• Documentation (including examples)
• Research and understanding

Disclosure

If you answered "yes" to using AI assistance, please provide a short disclosure indicating how you used AI assistance. This helps reviewers determine how much scrutiny to apply when reviewing your contribution. Example disclosures: "This PR was written primarily by Claude Code." or "I consulted ChatGPT to understand the codebase, but the proposed changes were fully authored manually by myself.".

This PR was written primarily by Claude Code under my direction. Claude identified the root cause by analyzing the workflow scripts and a failing CI run, and authored the uniq → sort -u replacements.

---

@stdlib-js/reviewers