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>

front-backend/justfile

@@ -0,0 +1,53 @@
+# Justfile for Post-ERG front-backend website
+
+# Default recipe - show available commands
+default:
+    @just --list
+
+# Start PHP development server
+serve:
+    @echo "Starting PHP development server on http://localhost:8000"
+    @echo "Using database: ../formulaire/test.db"
+    @echo "Press Ctrl+C to stop"
+    @php -S 127.0.0.1:8000
+
+# Test database connection
+test:
+    @echo "Testing database connection..."
+    @php test_db.php
+
+# Show database statistics
+stats:
+    @echo "=== Database Statistics ==="
+    @sqlite3 ../formulaire/test.db "SELECT COUNT(*) || ' total theses' FROM theses;"
+    @sqlite3 ../formulaire/test.db "SELECT COUNT(*) || ' published theses' FROM theses WHERE is_published = 1;"
+    @sqlite3 ../formulaire/test.db "SELECT COUNT(*) || ' authors' FROM authors;"
+    @sqlite3 ../formulaire/test.db "SELECT COUNT(*) || ' keywords' FROM keywords;"
+
+# Show recent published theses
+recent:
+    @echo "=== Recent Published Theses ==="
+    @sqlite3 -column -header ../formulaire/test.db "SELECT id, title, year, authors FROM v_theses_public ORDER BY year DESC, title LIMIT 10;"
+
+# Query database interactively
+query:
+    @sqlite3 ../formulaire/test.db
+
+# Show specific thesis details
+show id:
+    @sqlite3 -column -header ../formulaire/test.db "SELECT * FROM v_theses_full WHERE id = {{id}};"
+
+# Check PHP syntax for all PHP files
+check:
+    @echo "Checking PHP syntax..."
+    @php -l Database.php
+    @php -l index.php
+    @php -l memoire.php
+    @php -l apropos.php
+    @php -l contact.php
+    @php -l licences.php
+    @echo "✓ All files have valid syntax"
+
+# View error log
+logs:
+    @if [ -f error.log ]; then tail -n 50 error.log; else echo "No error log found"; fi