Add tie-handling tests for dispute voting

[hman38705]

Area: contracts/predict-iq/src/modules/resolution.rs

Problem: Tie behavior is not explicitly covered.

Testing gap: No test for equal top tallies.

Acceptance tests: Add test where two outcomes tie at max votes and assert expected error (likely NoMajorityReached) or explicit tie rule.

[Kingsman-99]

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This issue has been completed by @Kingsman-99 as part of the Stellar Wave Program's 3rd Wave 🥳

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