test(progress-tracker): add batch_submit_quiz_score edge case tests (fixes #641)

[lmduy2612]

Closes #641.

Summary of Changes

Adds comprehensive edge-case test coverage for batch_submit_quiz_score in contracts/progress-tracker:

• Batch size of 1: verifies that submitting a single score through batch behaves identically to single submit (test_batch_submit_quiz_score_batch_size_one_works_like_single).
• Duplicate quiz IDs: verifies that duplicate quizzes within the same batch are handled idempotently; the first is recorded and the duplicate is skipped without overwriting (test_batch_submit_quiz_score_with_duplicate_quiz_ids_skips_second).
• All entries valid: verifies complete batch submission and aggregate score calculation (test_batch_submit_quiz_score_all_entries_valid).
• Returned Vec filtering: verifies that the returned Vec includes only successfully submitted quiz IDs and strictly excludes all skipped / invalid entries (test_batch_submit_quiz_score_returned_vec_excludes_all_skipped_quizzes).

Verification

• cargo test --test progress_tests test_batch_submit_quiz_score: 14/14 tests pass.
• Code style adheres strictly to project conventions.