Add minimal utility functions for common operations

[meshackyaro]

Description

No helper functions for common tasks like amount formatting, address validation, etc.

Component

SDK

Difficulty

🟡 Medium

Tasks

• Add formatAmount / parseAmount utilities
• Add isValidAddress validator
• Add date formatting helpers
• Add CID validation utility
• Document utility functions

Acceptance Criteria

• Common utilities available
• Utilities well-tested
• Documentation with examples

Estimated Time

2 days