CSV import #12
Description
Users who already have testimonials in spreadsheets or exported from other platforms need a way to bring them in.
POST /api/v1/projects/{id}/import/csv — multipart upload, parses CSV, creates testimonials.
Expected columns: author_name, content, rating (optional), author_email (optional), author_title (optional), author_company (optional). Missing optional columns should be handled gracefully. Return a summary of imported vs skipped rows with reasons.
Dashboard needs a simple import page with file picker. Column mapping preview would be nice but not required for v0.1.