fix: preserve text-align on paste from Google Docs

[gpardhivvarma]

Summary

• Adds CSS text-align inline style fallback in parseAttrs.js so that paragraph alignment (center, right, justify) is preserved when pasting from Google Docs
• Maps CSS logical values (start/end) to physical OOXML justification values (left/right)
• Follows the same pattern as the existing spacing/indent CSS fallbacks from PR fix: preserve line spacing and indentation on Google Docs paste #2183

Test plan

• Added 8 unit tests covering all alignment values, invalid values, and combination with other CSS fallbacks
• All 717 test files pass (7167 tests)
• Manual test: paste centered/right-aligned/justified text from Google Docs and verify alignment is preserved