test: add fib regression tests and check runner for Issue #21 - #59

Description
Added regression tests and contract checks for fib in Dynamic-Programming/FastFibonacciNumber.js, and created the required check runner script.

Related Issue
Fixes: #21

Type of Change

• Bug Fix
• New Feature
• UI/UX Improvement
• Performance Improvement
• Tests
• Documentation
• Refactoring / Maintenance
• CI/CD

Changes Made

• Tested smallest valid input (n = 0) and ordinary input (n = 10) for fib in Dynamic-Programming/FastFibonacciNumber.js.
• Added regression checks in Dynamic-Programming/tests/FastFibonacciNumber.test.js.
• Created work/R50-T021/check.py to execute the test suite in non-watch mode and capture test output, fixture results, and tool versions.

Screenshots / Recordings
N/A

Testing

• Executed python3 work/R50-T021/check.py locally.
• Verified test suite passes for Dynamic-Programming/tests/FastFibonacciNumber.test.js.

Checklist

• I have tested my changes locally.
• I have added or updated tests, if needed.
• I have updated documentation, if needed.
• I have followed the project's coding guidelines.
• I have run the relevant tests and checks.
• I have addressed previous review feedback, if applicable.

Additional Notes
N/A