Summary

Refactor the Prisma schema for Phase 3 Wallet Management with production-ready PostgreSQL and Prisma practices.

Changes

• Replaced monetary Float fields with Decimal(18,2).
• Added wallet currency, appearance, description, default, and archive fields.
• Added hierarchical categories using a Prisma self-relation.
• Added receipt URL and location fields to transactions.
• Removed the redundant budget name field.
• Added indexes for wallet, category, transaction, budget, and authentication queries.
• Changed unsafe cascade deletes to restricted deletes for financial records.
• Prevented role deletion from cascading to users.
• Preserved the existing authentication behavior.
• Kept TransactionType as an enum while retaining flexible string values for currency and social providers.