feat(city): ✨ Implement bridge occupation multiplier and capture marking in City struct

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

src/simulator/crates/mc-city/src/city.rs

@@ -276,6 +276,11 @@ pub struct City {
     /// a city under sustained siege cannot out-regen incoming damage.
     #[serde(default)]
     pub last_attacked_turn: Option<u32>,
+
+    /// Turn this city was most recently captured. `None` = never captured.
+    /// Used to apply an occupation production penalty for OCCUPATION_TURNS after capture.
+    #[serde(default)]
+    pub captured_turn: Option<u32>,
 }
 
 impl Default for City {
@@ -300,6 +305,7 @@ impl Default for City {
             queues: HashMap::new(),
             building_yields: HashMap::new(),
             last_attacked_turn: None,
+            captured_turn: None,
         }
     }
 }
@@ -361,6 +367,7 @@ impl City {
             queues: HashMap::new(),
             building_yields: HashMap::new(),
             last_attacked_turn: None,
+            captured_turn: None,
         }
     }
 
@@ -664,6 +671,24 @@ impl City {
         self.hp == 0
     }
 
+    /// Record that this city was captured on `turn`.
+    /// Enables `occupation_production_mult` to apply the penalty.
+    pub fn mark_captured(&mut self, turn: u32) {
+        self.captured_turn = Some(turn);
+    }
+
+    /// Returns the production multiplier for `current_turn`.
+    /// Captured cities produce at 50% for `OCCUPATION_TURNS` turns
+    /// after capture to slow the attacker's production snowball.
+    pub fn occupation_production_mult(&self, current_turn: u32) -> f64 {
+        const OCCUPATION_TURNS: u32 = 5;
+        const OCCUPATION_PENALTY: f64 = 0.5;
+        match self.captured_turn {
+            Some(ct) if current_turn.saturating_sub(ct) < OCCUPATION_TURNS => OCCUPATION_PENALTY,
+            _ => 1.0,
+        }
+    }
+
     // ── Production queue (carried from production.rs, unchanged) ──
 
     /// Validate, charge, and enqueue an item into its producer building's queue.