feat(view): project CityView.culture_stored from the per-city CulturePool (Rail-1 Phase 0)

The live city_screen reads a per-city culture meter off the GDScript CityScript;
view_json had no equivalent, so the UI-pure-view migration couldn't render it from
getState(). project_cities now surfaces culture_stored from
PlayerState.culture_pool.city(c_idx) (the same accumulator mc-turn::process_culture
ticks for border expansion); 0.0 for a city with no pool entry.

Closes the last genuine Phase-0 projection gap (UnitView equipped/experience/movement/
posture + ResourceView golden_age were already projected — design-doc table was stale).

Test: projection_surfaces_city_culture_stored. mc-player-api lib 142/0.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/simulator/crates/mc-player-api/src/projection.rs

@@ -286,6 +286,15 @@ fn project_cities(
                 // and adapters can call view() across turns to observe progress.
                 // TRACKED: surface the canonical threshold via mc-city.
                 food_growth_threshold: 0.0,
+                // p3-25/Phase-0: real per-city culture accumulator from the
+                // player's CulturePool (the same value border expansion ticks
+                // in mc-turn::process_culture). 0.0 when the city has no pool
+                // entry yet (registered lazily on first culture yield).
+                culture_stored: player
+                    .culture_pool
+                    .city(c_idx)
+                    .map(|cc| cc.culture_stored as f32)
+                    .unwrap_or(0.0),
                 production_queue,
                 buildings,
                 // p3-25: real territory. CityState.owned_tiles is empty on a fresh
@@ -2142,6 +2151,38 @@ mod tests {
         );
     }
 
+    /// p3-25 Phase-0: `CityView.culture_stored` surfaces the per-city culture
+    /// accumulator from the player's `CulturePool` (the same meter the live
+    /// `city_screen` reads + border expansion ticks). A city with no pool entry
+    /// projects `0.0`.
+    #[test]
+    fn projection_surfaces_city_culture_stored() {
+        let mut state = GameState::default();
+        state.turn = 1;
+        state.grid = Some(mc_core::grid::GridState::new(20, 20));
+        let mut a = PlayerState::default();
+        a.player_index = 0;
+        a.city_positions = vec![(3, 4), (7, 8)];
+        a.cities = vec![mc_city::CityState::starter(), mc_city::CityState::starter()];
+        // City 0 accrues culture via its pool; city 1 has no pool entry.
+        a.culture_pool.register_city(0, 5.0);
+        a.culture_pool.tick_all();
+        a.culture_pool.tick_all();
+        state.players.push(a);
+
+        let view = project_view(&state, 0, /*omniscient=*/ true);
+        assert_eq!(view.cities.len(), 2);
+        assert!(
+            (view.cities[0].culture_stored - 10.0).abs() < 1e-3,
+            "registered city's stored culture must surface: {}",
+            view.cities[0].culture_stored
+        );
+        assert_eq!(
+            view.cities[1].culture_stored, 0.0,
+            "city with no pool entry projects 0.0"
+        );
+    }
+
     /// p3-24 rail-1: the diplomacy projection reads real OpenBorders/SharedMap
     /// agreement state from `state.trade_ledger` (replacing the former hardcoded
     /// `false`/empty stubs).

src/simulator/crates/mc-player-api/src/view.rs

@@ -142,6 +142,11 @@ pub struct CityView {
     pub food_stored: f32,
     /// Food needed for the next growth event.
     pub food_growth_threshold: f32,
+    /// Culture accumulated toward the next border expansion (mirrors the live
+    /// `CityScript` culture meter the `city_screen` reads). Sourced from the
+    /// player's `CulturePool` per-city state; `0.0` for a city with no pool entry.
+    #[serde(default)]
+    pub culture_stored: f32,
     /// Current production queue.
     pub production_queue: Vec<ProductionQueueEntry>,
     /// Buildings completed in this city.