feat: add Persian localization with RTL and Jalali calendar support

[AmirHosseinZg]

Summary

Adds Persian (fa) localization support to Sync-in, including:

• Persian frontend translations
• Persian backend notification translations
• Right-to-left (RTL) layout support
• Jalali calendar integration
• Locale registration for Day.js and Bootstrap
• Tests and documentation

Changes

Localization

• Added Persian locale registration on backend and frontend
• Added Persian notification translations
• Added Persian UI translations

RTL Support

• Dynamic dir and lang switching based on active locale
• Migrated RTL-relevant styling to CSS logical properties
• Audited remaining physical properties and documented intentional exceptions

Jalali Calendar

• Integrated jalaliday
• Added Jalali calendar rendering for Persian users
• Preserved Gregorian behavior for all other locales

Testing

• Added locale registration and normalization tests
• Verified all existing tests continue to pass

Validation

• Lint: PASS
• Tests: PASS (984 tests)
• Backend Build: PASS
• Frontend Build: PASS

Documentation

Implementation and validation reports are included under:

docs/contribution/

Notes

The implementation follows the repository's existing localization architecture and contribution guidelines without introducing architectural changes.

[cla-assistant]

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[johaven]

Hi @AmirHosseinZg,

Thank you for the PR. We’ll review it as soon as possible.

Could you please sign the CLA and rebase your branch?