Update README metadata: fix num_examples to 7861

Remove 11 old duplicate sharded files (pre-deduplication)

Update code-contests-plus-verl (Phase 1 intra-dedup)

Update dataset metadata

Fix README: correct processing statistics breakdown

Fix README: correct ground_truth format (inputs/outputs, not test_cases/templates)

Add comprehensive README with dataset documentation

Initial upload: 8,432 code contest problems in VERL format (1x config, 10MB test case limit)

initial commit