docs: codify entity systems pattern and record combat extensions

docs/SIMULATION_DEFINITIONS.md

@@ -24,8 +24,13 @@ Each executable action definition contains:
 - optional completion-cost resource ID and amount.
 
 The current actions are gather food, gather wood, feed animal, deposit food,
-deposit wood, withdraw food, patrol, study, eat, rest, sleep, and wander. Idle
-and dead are stable state sentinels, not executable action definitions.
+deposit wood, withdraw food, patrol, study, eat, rest, sleep, wander, and
+defend. Idle and dead are stable state sentinels, not executable action
+definitions.
+
+`defend` is the raid-response action: eligible strong villagers and guards
+prefer it during an active raid, travel to the guard post, and raise village
+safety while they work. Patrol activity sites accept it as a rally point.
 
 SimNPC reads default duration and preferred-profession metadata from these
 definitions. WorldViewManager reads target type and resource-action metadata
@@ -104,6 +109,15 @@ Combat, raid, and war narrative facts use the stable event types
 `combatant_hurt`, `combatant_killed`, `raid_started`, `war_resolved`,
 `war_aborted`, and `wolf_hunt`.
 
+## Enemy vocabulary
+
+`EnemyDefinition` is the data contract for hostile creatures and
+`SimulationEnemies` is the current registry. Each enemy carries a `kind`
+(raider/wolf), equipped weapon, health, move speed, body/accent colors, and a
+visual scale, so a new bear, bandit, or boar is mostly one definition plus a
+small `_build_*` visual hook on the shared `CreatureVisual` root. The current
+enemies are `enemy_raider` (sword) and `enemy_wolf` (claw).
+
 ## Validation
 
 The registry rejects: