[django-parity] Currency / region formatting

[ujeenet]

Django capability: Currency / region formatting
Django doc: https://docs.djangoproject.com/en/6.0/ref/settings/#languages
Status in rustango: MISSING
Category: 20. i18n / l10n

Gap (from audit)

⚠️ Prior investigation required

Before scoping a PR, grep the codebase for related primitives — rustango sometimes ships a better-shaped equivalent that doesn't match Django muscle memory (e.g. Django FileField ↔ rustango Media row + FK: same capability, different DX). Read the full row + neighboring rows in docs/django-parity-audit-2026-05-21.md before assuming "build from scratch."

Acceptance criteria

• Tri-dialect — cargo build --no-default-features --features sqlite,tenancy passes the litmus (or, if the capability is PG-only by language semantics, gate behind #[cfg(feature = "postgres")] and document)
• Lib unit test + one live test on the cheapest dialect for the new capability
• Audit row updated MISSING → SHIPPED with pointer in docs/django-parity-audit-2026-05-21.md