Adds the deterministic end-to-end proof p3-16's last bullet needed: in AI-vs-AI
self-play, once frontier-seek exploration brings a militarist into view of a
*weaker* rival, it dispatches a war-dec and the relation flips to War within 60
turns. Asymmetric armies (slot 2 weakened) so the aggressor clears its
superiority threshold on discovery. Pairs with the existing decide_diplomacy unit
cases (cautious-holds-at-parity / warmonger-strikes) to demonstrate
personality-driven war-decs manifest in actual play — the integration that was
blocked purely on discovery (p3-17). Shared self-play setup helper extracted.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>