[Feature] Database Integration for Document Storage and Retrieval

[P4ST4S]

Description:
All document generation happens in-memory only. There is no database to persist generated CGUs, user data, or application state. Documents are only downloadable and then lost.

Context/Rationale:
Without a database, users lose their work after downloading. A proper SaaS needs to store:

• User profiles and authentication data
• Generated documents with version history
• User preferences and templates
• Billing and subscription information
• Analytics and usage metrics

Implementation Suggestion / To-Do:

1. Choose database: PostgreSQL (Vercel Postgres/Supabase) or MongoDB
2. Set up ORM: Prisma or Drizzle ORM
3. Design schema with tables: users, documents, templates, subscriptions
4. Create API routes for CRUD operations
5. Implement document versioning and history
6. Add document search and filtering capabilities
7. Set up automated backups