feat: implement structured logging and environment-based log configuration in Flask backend

[A69SHUBHAM]

Summary

This PR replaces print statements with a structured logging system using Python's logging module and integrates environment-based configuration using python-dotenv.

Changes

• Replaced all print() statements with Python logging module
• Added structured log format with timestamps, module name, and log level
• Implemented log levels (INFO, WARNING, ERROR, DEBUG)
• Added logging for:
  • Incoming API requests
  • Outgoing responses
  • External API calls and failures
  • Exception handling
• Integrated environment-based configuration using .env
• Added LOG_LEVEL support to control verbosity (e.g., DEBUG, INFO)
• Restored and ensured load_dotenv() is called at startup

Why this is needed

The previous implementation relied on print statements, which are not suitable for production environments. This change improves debugging, observability, and provides structured, configurable logs for better monitoring.

Testing

• Verified logs for API requests and responses
• Tested error scenarios → errors logged correctly
• Tested LOG_LEVEL=DEBUG → verbose logs appear
• Confirmed .env variables are loaded properly
• Ensured no print statements remain in the backend

Impact

• Improves debugging and observability
• Makes backend more production-ready
• Provides consistent and structured logging
• Enables flexible configuration via environment variables

Closes #33