Fix critical security vulnerabilities and resource leaks

[Sunil56224972]

Hello! 👋
I was reviewing the project and found a few critical bugs and vulnerabilities. I've gone ahead and fixed them in this PR.

Summary of Fixes:

1. Directory Traversal / Arbitrary File Write (Exploit): Fixed an issue in patientRecord.py and movement.py where a user could input a crafted name (e.g., ../../../filename) to overwrite arbitrary files on the system. Filenames are now safely sanitized using regex.
2. JSON Injection (Exploit): The __str__ methods were manually concatenating JSON strings, making the system vulnerable to JSON injection if a name contained a double quote ("). This has been refactored to safely use Python's built-in json.dumps().
3. Missing Directory Crash (Bug): If the res/ directory did not exist, the application would hard crash with a FileNotFoundError. Added os.makedirs(..., exist_ok=True) before file operations to ensure the directory structure exists.
4. Zombie Camera Process (Resource Leak): When the application exited or crashed abruptly, the cv2.VideoCapture was not released, leaving the webcam light on and the device locked. Wrapped the ui.mainloop() inside main.py with a try...finally block to safely .release() the camera upon exit.

Let me know if you need any changes made!