test : add unit tests for formatNumber helper

[tmdeveloper007]

Summary

Add unit tests for formatNumber helper in src/utils/helpers.ts

Verification

npm test -- src/utils/tests/formatNumber.test.ts

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Hi, I am a GSSoC 2026 contributor and would like to work on this. Please assign this issue to me

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Thank you for assigning i ll work on this

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@tmdeveloper007 Hi! I've submitted this PR as part of GSSoC.