fix(desktop): 标题菜单光标与文字分列不再叠印

根因：页面标题行（panelY+24）与首行内容（MenuTopY）同为 y=320 造成两串文字叠印。修复：TitleScreen 布局新增 HeadingY/FirstItemY 分层与独立光标列（CursorX/CursorWidth/TextX），selectionRects 纯函数返回光标与文字矩形，回归测试断言逐行矩形不相交且标题行净空≥32px；渲染改为光标、文字分别绘制。

3 files changed, 58 insertions, 9 deletions

diff --git a/src/LivingVillage.Desktop.Tests/PrototypeTests.fs b/src/LivingVillage.Desktop.Tests/PrototypeTests.fs
index 524573f..c85287f 100644
--- a/src/LivingVillage.Desktop.Tests/PrototypeTests.fs
+++ b/src/LivingVillage.Desktop.Tests/PrototypeTests.fs
@@ -246,6 +246,22 @@ type PrototypeTests () =
         Assert.IsTrue(ChineseText.requiredUiLabels |> List.contains "精力")
 
     [<TestMethod>]
+    member _.TitleScreenSelectionCursorAndLabelNeverOverprint () =
+        let layout = TitleScreen.layout 1280 720
+
+        // Heading must sit fully above the first menu row (no same-line overprint).
+        Assert.IsTrue(layout.FirstItemY - layout.HeadingY >= 32, sprintf "heading clearance %d" (layout.FirstItemY - layout.HeadingY))
+
+        // Every menu row: cursor rectangle and label rectangle must be disjoint.
+        for rowIndex in 0 .. 5 do
+            let cursor, label = TitleScreen.selectionRects layout rowIndex
+            Assert.IsTrue(TitleScreen.rectsDisjoint cursor label, sprintf "row %d cursor overlaps label" rowIndex)
+            Assert.AreEqual<int>(cursor.Y, label.Y)
+
+        // Cursor column leaves real clearance: label starts beyond cursor + margin.
+        Assert.IsTrue(layout.TextX >= layout.CursorX + layout.CursorWidth)
+
+    [<TestMethod>]
     member _.TitleScreenLayoutIsDeterministicAndLayered () =
         let first = TitleScreen.layout 1280 720
         let second = TitleScreen.layout 1280 720
diff --git a/src/LivingVillage.Desktop/Game.fs b/src/LivingVillage.Desktop/Game.fs
index c8d0044..7337129 100644
--- a/src/LivingVillage.Desktop/Game.fs
+++ b/src/LivingVillage.Desktop/Game.fs
@@ -560,8 +560,12 @@ type LivingVillageGame() as this =
             PixelText.draw spriteBatch pixel cjkAtlas x y textScale color text
         let drawSelection (index: int) (label: string) (y: int) =
             let selected = index = menu.Selected
-            let prefix = if selected then ">" else " "
-            drawText innerX y (if selected then selectedColor else textColor) (sprintf "%s %s" prefix label)
+            let cursor, labelRect = TitleScreen.selectionRects layout index
+            if selected then
+                PixelText.draw spriteBatch pixel cjkAtlas cursor.X cursor.Y textScale selectedColor ">"
+            else
+                PixelText.draw spriteBatch pixel cjkAtlas cursor.X cursor.Y textScale mutedColor " "
+            PixelText.draw spriteBatch pixel cjkAtlas labelRect.X labelRect.Y textScale (if selected then selectedColor else textColor) label
         spriteBatch.Begin()
 
         // Layered dusk gradient: sky bands darken toward the horizon, never a flat block.
@@ -601,27 +605,27 @@ type LivingVillageGame() as this =
         // 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
+        let contentY = layout.FirstItemY
         match menu.Page with
         | MainMenu ->
-            drawText innerX (panelY + 24) mutedColor (ChineseText.menuHeading MainMenuHeading)
+            drawText innerX (layout.HeadingY) mutedColor (ChineseText.menuHeading MainMenuHeading)
             MenuState.items menu
             |> List.iteri (fun index item -> drawSelection index (MenuState.itemLabel item) (contentY + index * lineHeight))
             drawText innerX (panelY + panelHeight - 40) mutedColor "UP DOWN 选择 ENTER 确认"
         | Settings ->
-            drawText innerX (panelY + 24) mutedColor (ChineseText.menuHeading SettingsHeading)
+            drawText innerX (layout.HeadingY) mutedColor (ChineseText.menuHeading SettingsHeading)
             MenuState.settings
             |> List.iteri (fun index setting -> drawSelection index (MenuState.settingsLabel setting) (contentY + index * lineHeight))
             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 + 24) mutedColor (ChineseText.menuHeading ControlsHeading)
+            drawText innerX (layout.HeadingY) 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 - 40) mutedColor "ESC 返回"
         | LoadError ->
-            drawText innerX (panelY + 24) (Color(240, 130, 120)) "读取失败"
+            drawText innerX (layout.HeadingY) (Color(240, 130, 120)) "读取失败"
             let message = menu.Error |> Option.defaultValue "暂无存档"
             let visible = if message.Length > 24 then message.Substring(0, 24) else message
             drawText innerX contentY textColor visible
diff --git a/src/LivingVillage.Desktop/TitleScreen.fs b/src/LivingVillage.Desktop/TitleScreen.fs
index 8b1c5d5..00cf5b8 100644
--- a/src/LivingVillage.Desktop/TitleScreen.fs
+++ b/src/LivingVillage.Desktop/TitleScreen.fs
@@ -24,7 +24,31 @@ module TitleScreen =
           PanelX: int
           PanelY: int
           PanelWidth: int
-          PanelHeight: int }
+          PanelHeight: int
+          HeadingY: int
+          FirstItemY: int
+          CursorX: int
+          CursorWidth: int
+          TextX: int }
+
+    type TextRect =
+        { X: int
+          Y: int
+          Width: int
+          Height: int }
+
+    let rectsDisjoint (a: TextRect) (b: TextRect) : bool =
+        a.X + a.Width <= b.X
+        || b.X + b.Width <= a.X
+        || a.Y + a.Height <= b.Y
+        || b.Y + b.Height <= a.Y
+
+    /// Cursor and label rectangles for one menu row. The cursor is drawn in its own
+    /// column; the label always starts to the right of it, so they can never overprint.
+    let selectionRects (layout: TitleLayout) (rowIndex: int) : TextRect * TextRect =
+        let y = layout.FirstItemY + rowIndex * layout.MenuLineHeight
+        { X = layout.CursorX; Y = y; Width = layout.CursorWidth; Height = 16 },
+        { X = layout.TextX; Y = y; Width = layout.PanelX + layout.PanelWidth - layout.TextX - 24; Height = 16 }
 
     // Palette mirrors the VillageArt atlas: roof (45,49,57)/(30,33,38), water (54,116,145),
     // lantern paper (212,92,74). Purely decorative reuse of existing art colors.
@@ -82,4 +106,9 @@ module TitleScreen =
           PanelX = (width - panelWidth) / 2
           PanelY = height / 2 - 64
           PanelWidth = panelWidth
-          PanelHeight = min 360 (height - height / 2 - 40) }
+          PanelHeight = min 360 (height - height / 2 - 40)
+          HeadingY = height / 2 - 64 + 20
+          FirstItemY = height / 2 - 64 + 60
+          CursorX = (width - panelWidth) / 2 + 24
+          CursorWidth = 20
+          TextX = (width - panelWidth) / 2 + 24 + 20 + 12 }