Add SDK transaction retry safety policy

[El-swaggerito]

Description

Difficulty: Expert

Type: Security

Summary

Add a safety policy for retrying failed or uncertain transaction submissions.

Current Behaviour

Consumers may retry transactions without knowing whether a previous submission succeeded.

Expected Behaviour

The SDK should clearly separate safe retries from unsafe duplicate submissions.

Suggested Implementation

Design retry classification using transaction hash tracking, timeout handling, and status polling.

Files or Areas Likely Affected

src/transactions/
src/errors/
docs/
tests/

Acceptance Criteria

• Retryable and non-retryable failures are defined.
• Unknown submission state is represented separately.
• Tests cover timeout and duplicate-risk cases.
• Documentation explains safe retry behaviour.
• No blind resubmission is encouraged.

Additional Notes

This is a high-impact reliability and safety issue.

[vic2430]

I would like to work on this issue

[grantfox-oss]

🦊 GrantFox — @vic2430 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 #172)
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!

@vic2430's PR #200 was approved and merged by @El-swaggerito.

🏆 @vic2430: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (118 total points). Track your full progress on GrantFox.

👏 Great work, @vic2430! Keep contributing to Axionvera.