Add comprehensive thesis management system with database migration

This commit introduces a complete thesis management interface and migrates
the system from YAML-based storage to SQLite:

Core Changes:
- Add Database.php helper class with PDO connection and entity management
- Add list.php for viewing all theses with filtering and sorting
- Add edit.php for modifying existing thesis records
- Add import.php for migrating legacy YAML data to SQLite
- Add justfile with development tasks (serve, init-test-db, etc.)

Documentation:
- Add MIGRATION.md with complete migration guide and architecture docs
- Update README.md with database setup and Just recipe instructions
- Update .gitignore to exclude test databases and error logs

Modified Forms:
- Enhanced formulaire.php with transaction-based SQLite processing
- Updated index.php with database-driven form options
- Improved thanks.php to read from database views

The new architecture provides:
- Normalized database schema (19 tables, 2 views)
- Transaction safety and referential integrity
- CRUD operations for thesis management
- Filtering by year, orientation, AP program, publication status
- Secure file handling with metadata tracking

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

formulaire/.gitignore

@@ -0,0 +1,31 @@
+# Test database
+test.db
+
+# Error logs
+error.log
+
+# Uploaded files (for testing)
+data/theses/
+data/covers/
+
+# Keep the data directories but ignore contents
+!data/theses/.gitkeep
+!data/covers/.gitkeep
+
+# PHP session files
+sessions/
+
+# Composer
+vendor/
+composer.lock
+
+# OS files
+.DS_Store
+Thumbs.db
+
+# IDE
+.vscode/
+.idea/
+*.swp
+*.swo
+*~