feat: implement oracle fallback and resolution timeout with refund

[greatest0fallt1me]

Description:

Implement fallback oracle support and a resolution timeout; if primary oracle fails or timeout is reached, use fallback or trigger refund path.

Requirements and Context:

• Must be secure, tested, and documented
• Should allow configurable primary and fallback oracle per event
• Should allow resolution timeout (e.g., max time after event end to get oracle result)
• Should attempt fallback when primary fails; if both fail or timeout, allow admin refund or auto-refund
• Should emit events for fallback use and timeout
• Must not double-resolve or double-refund

Suggested Execution:

1. Fork the repo and create a branch

   git checkout -b feature/oracle-fallback-timeout

2. Implement changes

   • Write contract: src/lib.rs (resolve with fallback, timeout check)
   • Update oracles module: src/oracles.rs (fallback client)
   • Update types, storage, events
   • Add documentation and NatSpec-style comments

3. Test and commit

   • Run tests; cover primary fail, fallback success/fail, timeout, refund
   • Include test output and security notes

Example Commit Message:

feat: implement oracle fallback and resolution timeout with refund

Guidelines:

• Minimum 95 percent test coverage
• Clear documentation
• Timeframe: 96 hours

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[Georgechisom]

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[Sobilo34]

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Hi! Sobil is here

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[victorisiguzoruzoma874]

@victorisiguzoruzoma874 has applied to work on this issue as part of the Stellar Wave Program's 1st wave.

Hello maintainer, I would love to hug this issue and just it resolved, ETA 4hrs

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Congratulations, @victorisiguzoruzoma874! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on January 31, 2026.

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