Refactor: Rename misspelled function trian_and_predict to train_and_predict

[zizzii]

The core function 'trian_and_predict' in 'app/services/gaze_tracker.py' contains a typo. This refactor renames it to 'train_and_predict' to improve code readability and follow standard English spelling conventions.

Scope:

• Renamed function definition in 'app/services/gaze_tracker.py'.
• Updated all call sites within the same file.