feat(mc-combat): ✨ Add siege mechanics module with attack/defense logic and combat rules

Co-Authored-By: Lilith Autocommit <noreply@atlilith.com>

src/simulator/crates/mc-combat/src/siege.rs

@@ -23,13 +23,13 @@ const RANGED_CITY_HP_FRACTION: f32 = 0.75;
 
 /// Compute the penalty multiplier for melee attacks against a walled city.
 /// Returns a value < 1.0 that the attacker's effective strength is multiplied by.
-/// Scales by tier: 0=1.0, 1=0.70 (walls), 2=0.55 (castle).
+/// Scales by tier: 0=1.0, 1=0.75 (walls), 2=0.55 (castle).
 /// Paired with the melee-to-city damage fraction in resolver.rs that halves
 /// structural damage from non-siege melee attacks.
 pub fn melee_wall_penalty(wall_tier: i32) -> f32 {
     match wall_tier {
         0 => 1.0,
-        1 => 0.70,
+        1 => 0.75,
         _ => 0.55,
     }
 }
@@ -92,7 +92,7 @@ mod tests {
     #[test]
     fn melee_penalty_scales_by_tier() {
         assert!((melee_wall_penalty(0) - 1.0).abs() < 0.001);
-        assert!((melee_wall_penalty(1) - 0.70).abs() < 0.001);
+        assert!((melee_wall_penalty(1) - 0.75).abs() < 0.001);
         assert!((melee_wall_penalty(2) - 0.55).abs() < 0.001);
         assert!((melee_wall_penalty(3) - 0.55).abs() < 0.001);
     }