✅ Mammon no op when already owned by current player

Category	Ability
Status	Passing
Test	tests/test_abilities_complex.py::TestMammonTransferControl::test_mammon_no_op_when_already_owned_by_current_player

P1 owns Mammon and P1's main phase starts — no change.

Preconditions

• P1 owns Mammon (#053).

• P1's main phase is starting.

Action

• Fire MAIN_PHASE_START with side=P1.

Expected Postconditions

• Mammon.owner = P1 (unchanged)

Assertions

assert mammon_after.owner == Side.PLAYER_1