Refactor math/Collatz-Conjecture with memoization, input safeguarding and generator optimization

[Facelessism]

📝 Description

This PR refactors the math/Collatz-Conjectureto improve structure, performance and safety with added generator based sequence processing, memoization for repeated computations and runtime as well as input safeguards.

🔗 Linked Issue

Closes #571

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📋 Contribution Checklist

• My code strictly adheres to the project guidelines (Standard library only, procedural code, clean spacing).
• I have verified that my files are placed in the correct directory.
• I have tested my changes thoroughly on my local machine.
• I have included interactive emojis and clean console/UI outputs.
• GSSoC 2026: I have been formally assigned to this issue and noted it above.

[vercel]

@Facelessism is attempting to deploy a commit to the Anuj's projects Team on Vercel.

A member of the Team first needs to authorize it.

[Facelessism]

Hey @steam-bell-92
I’ve submitted the PR for the above issue.
Could you add the point multiplier labels to the PR if applicable?
Thank you

[github-actions]

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