feat(statement): add support to submit return results

[carlosala]

No description provided.

[Copilot]

Pull request overview

This PR adds comprehensive type definitions for statement submission results and updates the submit method to return detailed result information instead of void. The implementation includes backward compatibility handling for older API versions that returned undefined for successful submissions.

Key Changes:

• Introduces SubmitResult discriminated union type covering all possible submission outcomes (new, known, rejected, invalid)
• Updates the submit method signature to return Promise<SubmitResult> instead of Promise<void>
• Implements backward compatibility logic to handle API responses from versions prior to polkadot-sdk PR #10421

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
packages/sdk-statement/src/types.ts	Defines comprehensive SubmitResult type with discriminated unions for all possible submission outcomes including detailed rejection and validation failure reasons
packages/sdk-statement/src/statement-sdk.ts	Updates submit method return type to SubmitResult and adds backward compatibility handling for older API responses
packages/sdk-statement/src/api.ts	Updates internal API type signature to reflect optional SubmitResult return type

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[Copilot]

@carlosala I've opened a new pull request, #52, to work on those changes. Once the pull request is ready, I'll request review from you.