docs: add Vietnamese translation (README.vi-VN.md)

[bqhyuu]

Pull Request

Linked issue

Closes #

What & why

How it was tested

uv run pytest tests/ --tb=short -q
uv run ruff check code_review_graph/
uv run mypy code_review_graph/ --ignore-missing-imports --no-strict-optional

Checklist

• Tests added for new functionality
• All tests pass: uv run pytest tests/ --tb=short -q
• Linting passes: uv run ruff check code_review_graph/
• Type checking passes: uv run mypy code_review_graph/ --ignore-missing-imports --no-strict-optional
• Lines are at most 100 characters
• Docs updated where behavior changed (README, docs/, docstrings)

[iamraydoan]

Hi @bqhyuu,

Thanks for working on this! I didn't realize you had already opened a PR for the Vietnamese translation when I started working on mine.

Since I've also submitted PR #717, I wanted to share it here for context. PR #717 covers:

• Full translation of the entire document, keeping technical terms and CLI commands consistent.
• Complete Markdown structure (badges, code blocks, formatting) aligned with the original README.md.
• Updated navigation links for seamless integration.

@tirth8205 — feel free to review both PRs and let us know which approach works best for the repository!