fix: Complete currency consistency across onboarding and dashboard

[slimatic]

Summary

• Fixes hardcoded USD currency symbols in onboarding forms (step 4/8 - Cash Assets, Investments, Liabilities, Zakat Setup)
• Fixes dashboard components to use user's selected currency preference
• Fixes NisabYearRecordsPage to create records with user's currency
• Adds SPA routing nginx config for production builds

Changes

Onboarding Flow

• CashStep.tsx: Use user's currency symbol for Bank Accounts and Cash on Hand
• InvestmentsStep.tsx: Use user's currency symbol for all investment types
• LiabilitiesStep.tsx: Use user's currency symbol for liability inputs
• ZakatSetupStep.tsx: Use user's currency symbol for Zakat Paid input
• IdentityStep.tsx: Add missing currencies (TRY, EGP, IDR)

Dashboard & Charts

• ZakatDisplayCard.tsx: Use record.currency instead of hardcoded USD
• ZakatObligationsChart.tsx: Add currency prop, pass from AnalyticsPage
• WealthTrendChart.tsx: Add currency prop, pass from AnalyticsPage
• PaymentDistributionChart.tsx: Add currency prop, pass from AnalyticsPage
• Dashboard.tsx: Use user's currency preference

Nisab Records

• NisabYearRecordsPage.tsx: Use user's currency when creating records
• api.ts: Add currency parameter to createNisabYearRecord

Infrastructure

• docker/nginx-production.conf: New config with SPA routing support
• docker/Dockerfile.frontend: Use new nginx config for production

Testing

• Client tests: 411 passed, 15 skipped
• Server tests: 920 passed, 130 failed (pre-existing failures)