feat: Add import customer data feature from csv files

[dager-mohamed]

PR Summary

• Implemented full CRM import workflow: import-wizard.tsx, page.tsx, and app-sidebar.tsx now expose a four-step wizard with polished UI, template management, smart mapping suggestions, and navigation access.
• Added schema-detection and template utilities (schema-detection.ts, templates.ts, definitions.ts) powering auto-mapping, dedupe hints, and reusable configurations.
• Delivered server-side import pipeline in import.ts, covering session management, schema detection, validation, template CRUD, and import execution backed by new Prisma schema (schema.prisma, migration migration.sql, regenerated index.ts) plus wizard exports (index.ts).