Implement comprehensive SDK error hierarchy with error codes

[p3ris0n]

Summary

Replace generic Error throws with a structured error hierarchy that provides error codes, human-readable messages, recovery suggestions.

Requirements

• Create sdk/src/errors.ts
• Base class: BcForgeError
• Specific subclasses: NetworkError, SimulationError, TransactionError, ContractError, ValidationError
• Parse Soroban panic messages
• Add isRetryable field

[Opulencechuks]

@Opulencechuks has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

I would like to work on this because i can implement it having worked on similar issues

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[drips-wave]

Congratulations, @Opulencechuks! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

🧑‍💻 @Opulencechuks: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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[drips-wave]

This issue has been completed by @Opulencechuks as part of the Stellar Wave Program's 5th Wave 🥳

😎 @Opulencechuks: You earned 100 Points for completing this issue! After the current Wave ends, you'll be eligible for a percentage of the Wave's reward pool based on the percentage of total points you've earned. Learn more here. You can also Leave a review to share your experience working on this issue.

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