fix: correctly percent encode UTF-8 bytes

[MahmadHadi]

Resolves #15595.

Description

What is the purpose of this pull request?

This pull request:

• Fixes percent encoding for single-digit hexadecimal bytes and preserves ASCII characters following multibyte UTF-8 characters.

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

• @stdlib/string/base/percent-encode produces malformed encoding and silently drops characters #15595

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

I consulted ChatGPT to understand the issue and codebase and used it to help identify and implement the fix.

---

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