Add input validation to coin change algorithms

[MayankSharma-2812]

Improves robustness by validating inputs and handling edge cases while preserving the existing dynamic programming logic.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 79.83193% with 24 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.84%. Comparing base (08d8c6b) to head (ff5be5b).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
Dynamic-Programming/CoinChange.js	79.48%	8 Missing ⚠️
Sliding-Windows/LongestSubarrayWithSumAtMost.js	62.50%	6 Missing ⚠️
Search/BinarySearch.js	66.66%	4 Missing ⚠️
Sorts/BubbleSort.js	82.60%	4 Missing ⚠️
Sorts/SelectionSort.js	71.42%	2 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## master #1878 +/- ##
==========================================
- Coverage 85.91% 85.84% -0.08% 
==========================================
Files 379 379 Lines 19778 19839 +61 Branches 3015 3047 +32 ==========================================
+ Hits 16993 17030 +37 - Misses 2785 2809 +24 

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