Add bump-to-attack, death and a sim event queue

A step onto an occupied tile is now an attack: the geometry rule is checked
against terrain only and the target tile decides between move and bump.
Entities carry an attack stat; at zero hp they are removed. The sim reports
Attacked/Died through an event queue the game drains after every movement
window — the seam for sound, log, camera effects and spawns. Click-to-move
treats an occupied goal as a target but detours around entities in the way;
the player's death ends the game.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

sim/src/entity.rs

@@ -13,10 +13,12 @@ pub struct Entity {
     pub pos:     (i16, i16),
     pub hp:      u16,
     pub hp_max:  u16,
+    /// Damage dealt per bump.
+    pub attack:  u16,
 }
 
 impl Entity {
-    pub fn new(id: u32, kind: EntityKind, type_id: u16, pos: (i16, i16), hp: u16) -> Self {
+    pub fn new(id: u32, kind: EntityKind, type_id: u16, pos: (i16, i16), hp: u16, attack: u16) -> Self {
         Self {
             id,
             kind,
@@ -24,6 +26,7 @@ impl Entity {
             pos,
             hp,
             hp_max: hp,
+            attack,
         }
     }
 }