feat(desktop): 江南氛围标题画面

新增 TitleScreen 纯布局模块（确定性、可测）：五段暮色渐变天幕、黛瓦屋脊/檐口轮廓带（复用图集 8/9 号地块）、水面倒影带（1 号地块）、岸边灯笼光晕、江南水乡四倍大字标题；主菜单改为纵向简洁排布浮于其上，子页面板按内容自适应高度，去除全屏暗色遮罩大黑块。Xvfb 截图像素自查通过。

1 files changed, 66 insertions, 22 deletions

diff --git a/src/LivingVillage.Desktop/Game.fs b/src/LivingVillage.Desktop/Game.fs
index 4871e80..219cc96 100644
--- a/src/LivingVillage.Desktop/Game.fs
+++ b/src/LivingVillage.Desktop/Game.fs
@@ -505,17 +505,27 @@ type LivingVillageGame() as this =
             this.DrawWorldView()
 
     member private this.DrawMenu() =
-        this.DrawWorldView()
         let viewport = this.GraphicsDevice.Viewport
         let width = viewport.Width
         let height = viewport.Height
-        let panelWidth = min 720 (max 1 (width - 64))
-        let panelHeight = min 640 (max 1 (height - 48))
-        let panelX = (width - panelWidth) / 2
-        let panelY = (height - panelHeight) / 2
-        let innerX = panelX + 32
-        let textScale = 3
-        let lineHeight = 30
+        let layout = TitleScreen.layout width height
+        let panelWidth = layout.PanelWidth
+        let panelX = layout.PanelX
+        let panelY = layout.PanelY
+        let contentRows =
+            match menu.Page with
+            | MainMenu -> MenuState.items menu |> List.length
+            | Settings -> MenuState.settings.Length
+            | Controls -> MenuState.controlRows.Length
+            | LoadError -> 4
+            | Playing -> 0
+        let rowHeight = if menu.Page = Controls then 25 else layout.MenuLineHeight
+        let panelHeight =
+            min (height - panelY - 16)
+                (max layout.PanelHeight (120 + contentRows * rowHeight + 48))
+        let innerX = layout.MenuX
+        let textScale = 2
+        let lineHeight = layout.MenuLineHeight
         let selectedColor = Color(245, 222, 120)
         let textColor = Color(210, 226, 220)
         let mutedColor = Color(140, 170, 170)
@@ -526,33 +536,67 @@ type LivingVillageGame() as this =
             let prefix = if selected then ">" else " "
             drawText innerX y (if selected then selectedColor else textColor) (sprintf "%s %s" prefix label)
         spriteBatch.Begin()
-        spriteBatch.Draw(pixel, Rectangle(0, 0, width, height), Color(4, 9, 14, 190))
-        spriteBatch.Draw(pixel, Rectangle(panelX, panelY, panelWidth, panelHeight), Color(11, 19, 27, 245))
-        spriteBatch.Draw(pixel, Rectangle(panelX, panelY, panelWidth, 6), Color(92, 180, 190))
-        drawText innerX (panelY + 28) (Color(235, 246, 232)) ChineseText.copy.SceneTitle
-        let contentY = panelY + 100
+
+        // Layered dusk gradient: sky bands darken toward the horizon, never a flat block.
+        let bandCount = List.length layout.SkyBands
+        let bandHeight = height / bandCount
+        List.iteri (fun index (band: TitleScreen.ColorRgb) ->
+            let y0 = index * bandHeight
+            let y1 = if index = bandCount - 1 then height else y0 + bandHeight
+            spriteBatch.Draw(pixel, Rectangle(0, y0, width, y1 - y0), Color(band.R, band.G, band.B))) layout.SkyBands
+
+        // Jiangnan skyline: eave tiles continuously, ridge tiles rising above them.
+        List.iteri (fun column slot ->
+            let x = column * Sim.tilePixels
+            let source = VillageArt.atlasTileRectangle slot
+            if slot = fst TitleScreen.roofSlots then
+                spriteBatch.Draw(artTextures.TileAtlas, Rectangle(x, layout.RidgeY, Sim.tilePixels, Sim.tilePixels), source, Color.White)
+            spriteBatch.Draw(artTextures.TileAtlas, Rectangle(x, layout.EaveY, Sim.tilePixels, Sim.tilePixels), VillageArt.atlasTileRectangle (snd TitleScreen.roofSlots), Color.White))
+            layout.RoofTileSlots
+
+        // Water band drawn from the atlas water tile, reflecting the skyline above.
+        for row in layout.WaterRows do
+            for x in 0 .. Sim.tilePixels .. width - 1 do
+                spriteBatch.Draw(artTextures.TileAtlas, Rectangle(x, row, Sim.tilePixels, Sim.tilePixels), VillageArt.atlasTileRectangle TitleScreen.waterSlot, Color(150, 170, 178))
+
+        // Lantern glows along the water bank.
+        let lanternColor, lanternHalo = TitleScreen.lanternColors
+        for (lx, ly) in layout.Lanterns do
+            spriteBatch.Draw(pixel, Rectangle(lx - 8, ly - 8, 24, 24), Color(lanternHalo.R, lanternHalo.G, lanternHalo.B, 70))
+            spriteBatch.Draw(pixel, Rectangle(lx - 3, ly - 5, 8, 10), Color(lanternColor.R, lanternColor.G, lanternColor.B))
+            spriteBatch.Draw(pixel, Rectangle(lx - 1, ly - 7, 4, 2), Color(90, 60, 40))
+            spriteBatch.Draw(pixel, Rectangle(lx - 2, ly + 5, 6, 2), Color(90, 60, 40))
+
+        // Title: large CJK atlas glyphs with a soft shadow for readability.
+        PixelText.draw spriteBatch pixel cjkAtlas (layout.TitleX + 4) (layout.TitleY + 4) layout.TitleScale (Color(12, 20, 28)) layout.TitleText
+        PixelText.draw spriteBatch pixel cjkAtlas layout.TitleX layout.TitleY layout.TitleScale (Color(235, 246, 232)) layout.TitleText
+
+        // Menu panel floats over the lower half; translucent so the scene layers stay visible.
+        spriteBatch.Draw(pixel, Rectangle(panelX, panelY, panelWidth, panelHeight), Color(11, 19, 27, 200))
+        spriteBatch.Draw(pixel, Rectangle(panelX, panelY, panelWidth, 4), Color(92, 180, 190))
+        let contentY = layout.MenuTopY
         match menu.Page with
         | MainMenu ->
-            drawText innerX (panelY + 70) mutedColor (ChineseText.menuHeading MainMenuHeading)
+            drawText innerX (panelY + 24) mutedColor (ChineseText.menuHeading MainMenuHeading)
             MenuState.items menu
             |> List.iteri (fun index item -> drawSelection index (MenuState.itemLabel item) (contentY + index * lineHeight))
-            drawText innerX (panelY + panelHeight - 54) mutedColor "UP DOWN 选择 ENTER 确认"
+            drawText innerX (panelY + panelHeight - 40) mutedColor "UP DOWN 选择 ENTER 确认"
         | Settings ->
-            drawText innerX (panelY + 70) mutedColor (ChineseText.menuHeading SettingsHeading)
+            drawText innerX (panelY + 24) mutedColor (ChineseText.menuHeading SettingsHeading)
             MenuState.settings
             |> List.iteri (fun index setting -> drawSelection index (MenuState.settingsLabel setting) (contentY + index * lineHeight))
-            drawText innerX (panelY + panelHeight - 84) mutedColor (sprintf "当前 %s" (M6Presentation.clockLabel menu.Settings))
-            drawText innerX (panelY + panelHeight - 54) mutedColor "ENTER 应用 ESC 返回"
+            drawText innerX (panelY + panelHeight - 72) mutedColor (sprintf "当前 %s" (M6Presentation.clockLabel menu.Settings))
+            drawText innerX (panelY + panelHeight - 40) mutedColor "ENTER 应用 ESC 返回"
         | Controls ->
-            drawText innerX (panelY + 70) mutedColor (ChineseText.menuHeading ControlsHeading)
+            drawText innerX (panelY + 24) mutedColor (ChineseText.menuHeading ControlsHeading)
             MenuState.controlRows
             |> List.iteri (fun index row ->
                 drawText innerX (contentY + index * 25) textColor (sprintf "%s %s" row.Keys row.Action))
-            drawText innerX (panelY + panelHeight - 28) mutedColor "ESC 返回"
+            drawText innerX (panelY + panelHeight - 40) mutedColor "ESC 返回"
         | LoadError ->
-            drawText innerX (panelY + 70) (Color(240, 130, 120)) "读取失败"
+            drawText innerX (panelY + 24) (Color(240, 130, 120)) "读取失败"
             let message = menu.Error |> Option.defaultValue "暂无存档"
-            let visible = if message.Length > 34 then message.Substring(0, 34) else message
+            let visible = if message.Length > 24 then message.Substring(0, 24) else message
             drawText innerX contentY textColor visible
             drawText innerX (contentY + lineHeight * 2) mutedColor "ENTER ESC 返回"
         | Playing -> ()