nx_breeder_arena_gate.nx

nx_breeder_arena_gate.nx -- proves the COMPOSED loop is a game: a player moving in a real world with collision, wilds that hunt him, duels that resolve, capture that preserves identity, and breeding that pays off -- winnable AND losable, bit-deterministic, with the world's invariants intact all run. This is the gate that EARNS the gamebench physics-collision flip; without it that flip would be a claim. MUTATION TARGET (documented): make the player invulnerable (BA_LOSS_HP=0) => the reckless policy can no longer lose => stakes collapse => nx_game_depth caps the score below SHALLOW => T2 and T6 RED. license_tier: ORIGINAL