Add quiz progress persistence for session resume

[nicholaspsmith]

Summary

• Saves quiz progress to PostgreSQL so users can resume sessions after refresh
• Tracks which questions have been answered and current quiz state
• Automatically prompts users to resume incomplete quizzes when returning to the study page

Key Components Added

• Database Schema: Added study_session_progress table to track quiz state per user and session
• Database Operations: Implemented CRUD operations for session progress in lib/db/study-sessions.ts
• API Endpoints: Added routes for saving and retrieving session progress (/api/sessions/progress)
• UI Components: Created ResumeSessionDialog to prompt users to resume incomplete sessions
• Integration: Connected session resumption to create and complete quiz routes and study page

Test Coverage

• 106 tests passing
• Unit tests for database operations and API endpoints
• Tests validate session persistence and resume functionality