Add Number Spiral (CSES 1071) solution with explanation and test cases

[Aditya12604]

Description
This PR adds a C++ solution for the CSES problem:
"Number Spiral" (Problem ID: 1071)

• Problem Link: https://cses.fi/problemset/task/1071/
• Includes detailed explanation, complexity analysis, and test cases
• Code follows clean structure and uses clear comments
• Self-contained with main() function for demonstration

Folder Structure
Placed under: CPP/patterns/Pattern/NumberSpiral_CSES1071.cpp

Highlights

• O(1) time complexity per query
• Well-documented logic with descriptive comments
• Includes edge cases and example test cases with expected outputs

Test Cases
Includes two test cases within main() showing sample input/output.

Hacktoberfest
This PR is made for Hacktoberfest 2025.

[github-actions]

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[github-actions]

🤖 Automated PR Status

🔍 Code Validation

✅ Passed - File naming and structure look good!

🧪 Compilation Tests

✅ Passed - All code compiles successfully!

📋 Overall Status

🎉 Ready for Review - Your PR has passed all automated checks!
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