[Zig] Expand Hex module operations

[roninjin10]

Summary

Expand Hex module operations in Zig to match TypeScript's 30+ functions.

Missing Operations

Manipulation

• pad - Pad hex to length
• trim - Trim leading zeros
• xor - XOR two hex values

Generation

• random - Generate random hex

Validation

• validateHex - Validate hex string format
• isHex - Check if valid hex

Size Operations

• size - Get byte size of hex
• isEmpty - Check if empty

Bitwise

• Bitwise operations on hex values

Current State

Zig has core hex operations but missing utility functions.

Note: Issue created by Claude AI assistant, not @roninjin10 or @fucory