[vinayaksingh108]

Summary

• Make nfc() round and pad decimal places when a precision is provided.
• Preserve the existing formatting when precision is omitted.
• Add regression tests for rounding, padding, zero precision, negative values, and arrays.

Validation

• Focused utility tests: 31 passed
• Oxlint: passed for the changed files

AI use

AI assistance was used to help implement and validate this change; I reviewed the changes and tests.

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