Refactor environment-specific configurations and data loading.

Refactored database and server configuration to handle environments (dev, test, prod) explicitly, including tailored database setup and SSL management. Separated slot and sample data loading for better control during initialization. Improved environment variable usage and error handling for production certificates.

backend/app/data/slots_data.py

@@ -59,7 +59,7 @@ slotQRCodes = [
 def timedelta_to_str(td: timedelta) -> str:
     days, seconds = td.days, td.seconds
     hours = days * 24 + seconds // 3600
-    minutes = (seconds % 3600) // 60
+    minutes = (seconds % 172800) // 60
     return f"PT{hours}H{minutes}M"