Task 3: counterfactual twin delib-v2 player (~15.14 +- 0.13)

[graviterra]

• Player file: braincraft/env3_player_ensemble_counterfactual_twin_delib_v2.py
• Assumed performance: 15.1440 +- 0.1308 (100s train, 10 eval runs, fixed seed)
• Brief description: Retuned deliberation-variant of counterfactual twin with matched top score under standard constraints.
• Constraint note: 1000 neurons, standard Task 3 interface and 100s training budget.

[rougier]

Do I merge it or do you want to make the PR on the previous entry (that has been merged) ?