Add SDK Soroban request simulation design

[El-swaggerito]

Description

Difficulty: Expert

Type: Feature

Summary

Design how the SDK should simulate Soroban contract calls before signing or submission.

Current Behaviour

State-changing contract calls may require simulation before execution.

Expected Behaviour

The SDK should define a safe simulation step and how simulation results are exposed.

Suggested Implementation

Document or implement simulation inputs, outputs, errors, and relation to signing.

Files or Areas Likely Affected

src/soroban/
src/transactions/
src/types/
docs/

Acceptance Criteria

• Simulation flow is designed.
• Simulation result type is defined.
• Failure cases are covered.
• Signing boundary is explained.
• Documentation includes examples.

Additional Notes

This should support future real vault calls.

[Truphile]

Hi! I'd like to work on this.

My first step will be to understand the current implementation and any architectural constraints that influenced it. I'll then implement the requested behavior with minimal impact on existing interfaces, ensuring the change is isolated, testable, and consistent with the project's established patterns. I'll extend the test suite to cover functional behavior, failure modes, and regression scenarios before opening a PR.

[grantfox-oss]

🦊 GrantFox — @Truphile has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #217)
2. Your PR will be reviewed by the Axionvera maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign | FWC26 campaign!

@Truphile's PR #350 was approved and merged by @El-swaggerito.

🏆 @Truphile: You earned 40 FoxPoints for this contribution! Your current tier: Builder (1,409 total points). Track your full progress on GrantFox.

👏 Great work, @Truphile! Keep contributing to Axionvera.