Harden the state-emit rule to reduce under-reporting

Rewrite the global emit rule to be directive: treat narration as
authoritative and record numeric changes (damage, healing, time, emotion
shifts, fights intensifying), not just easy on/off flags — updating every
stat the scene affected. Also firm up the demo scenario's AI instructions
to reflect combat outcomes in the numbers each turn. Helps weaker free
models emit numeric deltas; the emit rule applies live so all RPG
adventures benefit immediately.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/app/seed_data/04-rpg-world-state.json

@@ -4,7 +4,7 @@
   "prompt": "Dawn breaks grey over the treeline as you and Gwen crouch at the edge of the bandit camp. Smoke curls from a dying fire; three bedrolls lie empty. Somewhere ahead, the stolen caravan strongbox waits.\n\nGwen checks her bowstring and looks to you. \"Quiet, or loud?\"",
   "memory": "The player and Gwen, a loyal ranger ally, are raiding a bandit camp to recover a stolen strongbox. The player is a capable adventurer. This is a dangerous but winnable encounter.",
   "authors_note": "Keep it tense and consequential. Reckless moves should cost health; clever ones should pay off. Gwen reacts to how the player treats her.",
-  "ai_instructions": "Write in second person, present tense. End each reply where the player can act. Let the world state guide the fiction — if the player is badly hurt, show it.",
+  "ai_instructions": "Write in second person, present tense. End each reply where the player can act. Let the world state guide the fiction — if the player is badly hurt, show it. In any fight, reflect the outcome in the numbers every turn: reduce the health of whoever is struck, raise the bandit leader's aggression as he is pressed, and adjust Gwen's trust based on how the player treats her.",
   "tags": "demo, rpg, world-state, combat, short",
   "stat_schema": {
     "world": {