feat(api-gdext): ✨ Add Rust bindings for yield registration (food/energy) and expose GDScript functions to manage city yields

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

src/simulator/api-gdext/src/lib.rs

@@ -818,6 +818,20 @@ impl GdCity {
         self.inner.has_building(&building.to_string())
     }
 
+    /// Register a building's flat yield bonuses. GDScript passes the
+    /// five per-turn bonuses parsed from the building JSON's `effects` array.
+    /// The city applies these in `get_yields` for each owned building.
+    #[func]
+    fn register_building_yields(
+        &mut self, building: GString,
+        food: f64, production: f64, gold: f64, culture: f64, science: f64,
+    ) {
+        self.inner.register_building_yields(
+            building.to_string(),
+            mc_city::CityYields { food, production, gold, culture, science },
+        );
+    }
+
     /// Load items from a JSON array `[ { id, production: { building, secondary_building?,
     /// production_cost, materials?, requires_tech? }, ... }, ... ]`. The DataLoader passes
     /// the merged item list from `public/resources/items/*.json`. Items without a