Implement Contract Fuzz Testing

[Mosas2000]

## Description

Add fuzz tests for the Soroban contract to explore edge cases and malformed inputs.

## Requirements and context

- Input mutation

• State transition fuzzing

• Failure classification

• Deterministic seeds

• CI compatibility

• Coverage reporting

  Suggested execution

  Fork the repo and create a branch

  git checkout -b feature/testing-contract-fuzz

  Implement changes

  • Create fuzz testing harness

• Target key contract entrypoints

• Add regression seeds

• Document fuzz workflow

  Example commit message

  test: implement contract fuzz testing

  Guidelines

  • Assignment required before starting
  • PR must include a closing reference to this issue
  • Include screenshots or examples where applicable
  • Timeframe: 72 hours