Feat/issue 808 cli input validation

[Shashank-8p]

📝 Description

Resolves critical ValueError crashes across the Python CLI applications by standardizing user input handling.

Architectural Changes Implemented:

• Centralized Validation: Discovered and integrated the pre-existing utils/validation.py module into the CLI games (e.g., Number-Sliding-Puzzle.py).
• Crash Prevention: Replaced raw int(input()) and localized, redundant try-except blocks with get_int() and get_yes_no(). These utilities enforce infinite retry loops, ensuring the application gracefully handles non-numeric or empty inputs without hard-crashing.
• Code Reduction: Removed boilerplate validation logic from individual game scripts, reducing technical debt and improving maintainability.

🔗 Linked Issue

Closes #808

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📋 Contribution Checklist

• My code strictly adheres to the project guidelines.
• I have tested the changes locally by attempting to input invalid data (e.g., letters instead of numbers) and verified the application recovers gracefully.
• GSSoC 2026: I have been formally assigned to this issue and noted it above.

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