docs: add Persian quickstart translation

[mmdverse]

Summary

This starts the Persian (fa) documentation effort with a focused Quickstart chapter.

• Adds docs/source/fa/quick-start.md
• Adds a minimal Persian _toctree.yml containing the translated chapter
• Registers fa in the main and PR documentation build workflows

Reader-facing prose is translated while code samples, API names, URLs, anchors, CLI commands, and file paths are preserved.

Closes #4686

Validation

• doc-builder build huggingface_hub docs/source/fa/ --language fa --build_dir /tmp/hf-fa-doc-build
• Verified that fenced code blocks, link targets, anchors, and admonition counts match the English source.

@Wauplin @stevhliu

Unicode note

Persian orthography uses U+200C zero-width non-joiners. The translation contains no Unicode bidi override or isolate control characters.

[mmdverse]

Hi! Just following up in case any changes or additional context would help with this translation. I’m happy to update the PR if needed. Thanks for your time.