fix(api): make request identifiers exclusive

[kriss39]

Which Linear task is linked to this PR?

None.

Why was it implemented this way?

ContractCallsQuoteRequest has two mutually exclusive quote modes, but its union accepted an object containing both fromAmount and toAmount. Similarly, GetStatusRequest accepted both txHash and taskId.

Adding the opposite key as ?: never makes these alternatives exclusive while preserving valid request shapes. The accompanying type-contract tests cover both valid modes and ensure the two ambiguous forms remain rejected.

Visual showcase (Screenshots or Videos)

Not applicable.

Checklist before requesting a review

• I have performed a self-review and testing of my code.
• This pull request is focused and addresses a single problem.
• If this PR modifies the Types API or adds new features that require documentation, I have updated the documentation in the public-docs repository.

Verification

• tsc --project tests/tsconfig.json
• CJS, ESM, and declaration builds using the package build compiler arguments
• prettier --check src/api.ts tests/api.contract.ts