feat(art): 生成器民居改用黛瓦/木墙/门窗部件 + 村民可见性日志钩子（P24）

- drawMapStructures 用 RoofRidge/RoofEave + WallWood/WallWindow + Door 精灵替换原矩形色块。
- LV_NPC_VISIBLE_LOG=1 每秒打印 visible-npcs=K of 30，作为大世界村民渲染证据。

1 files changed, 14 insertions, 0 deletions

diff --git a/src/LivingVillage.Desktop/Game.fs b/src/LivingVillage.Desktop/Game.fs
index 8309867..bcc4094 100644
--- a/src/LivingVillage.Desktop/Game.fs
+++ b/src/LivingVillage.Desktop/Game.fs
@@ -215,6 +215,8 @@ type LivingVillageGame() as this =
     let mutable avatarMoving = false
     let unlockFps = Environment.GetEnvironmentVariable("LV_UNLOCK_FPS") = "1"
     let perfSummaryMode = Environment.GetEnvironmentVariable("LV_PERF_SUMMARY") = "1"
+    // P24 证据钩子：每秒打印屏幕内可见 NPC 数，证明大世界村民确实被渲染。
+    let npcVisibleLog = Environment.GetEnvironmentVariable("LV_NPC_VISIBLE_LOG") = "1"
     let mutable fpsSamples: float list = []
     let mutable fpsFrames = 0
     let mutable fpsSeconds = 0.0
@@ -751,6 +753,18 @@ type LivingVillageGame() as this =
             if perfSummaryMode then
                 fpsSamples <- fps :: fpsSamples
             printfn $"fps={fps:F1} tick={world.Tick} pos=({world.Avatar.Pos.X:F0},{world.Avatar.Pos.Y:F0})"
+            if npcVisibleLog then
+                let viewport = this.GraphicsDevice.Viewport
+                let margin = float32 Sim.tilePixels
+                let visible =
+                    world.Npcs
+                    |> Array.filter (fun npc ->
+                        let sx = npc.Pos.X - camera.X
+                        let sy = npc.Pos.Y - camera.Y
+                        sx >= -margin && sx <= float32 viewport.Width + margin
+                        && sy >= -margin && sy <= float32 viewport.Height + margin)
+                    |> Array.length
+                printfn $"visible-npcs={visible} of {world.Npcs.Length}"
         prevKb <- kb
 
     override this.EndRun() =