Add test suite

[neyec]

Set up comprehensive testing across all services.

Backend

• Unit tests for API routes (auth, projects, documents, reporting, chat)
• Service layer tests (risk evaluation, seed, document processing)
• Database model and migration tests
• Test fixtures and factories for common entities

Pipelines

• Unit tests for document processing (text extraction, summarisation)
• Integration tests for the processing endpoint

Frontend

• Component tests (sidebar, checklist panel, risk banner, project provider)
• Page-level tests (login, register, documents, reporting, frameworks)
• API client mock setup
• E2E tests for critical user flows (login, project creation, document upload)

Infrastructure

• CI pipeline for running tests on PR
• Coverage reporting