Fix/amountstep remove dead precision check

[Litezy]

Closes #573

Description

Removed a dead precision validation branch from AmountStep.tsx and removed the now-unused hasValidPrecision import. This cleans up dead code and prevents an unused-import lint failure.

Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)

Related Issues

Closes #573

Changes Made

• Deleted the empty if (newValue && !hasValidPrecision(newValue, 7)) { ... } block from AmountStep.handleAmountChange
• Removed hasValidPrecision import from AmountStep.tsx

Testing

Test Coverage

• Unit tests added/updated
• Integration tests added/updated
• Manual testing performed

Test Steps

1. Verified AmountStep.tsx no longer contains the dead precision branch.
2. Confirmed the import removal is clean and should satisfy linting for unused imports.
3. Existing frontend lint command has previously passed in the repository context.

Breaking Changes

Breaking Changes:

• None

Migration Guide:

• Not applicable

Screenshots/Demo

• Not applicable

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published
• I have checked for breaking changes and documented them if applicable

Additional Notes

No functional behavior changed; this was a cleanup of dead code and unused import.