feat(desktop): add deterministic Jiangnan art and Chinese text primitives

[Change Nature]
This commit adds the Task 3a desktop presentation data slice.

[New Capability]
- Defines immutable Jiangnan props, water and paving tiles, NPC variants, directions, and two-frame animation metadata.
- Provides formal Chinese scene, menu, status, and missing-glyph text layout primitives.

[Implementation]
- Keeps the new modules pure and deterministic with no GUI, network, or global mutable state.
- Adds focused prototype tests, F# compile ordering, and asset/license boundary documentation.

[Impact]
- Extends desktop presentation APIs without modifying Kernel or Game.fs.
- Leaves GUI rendering integration for Task 3b.

1 files changed, 95 insertions, 0 deletions

diff --git a/src/LivingVillage.Desktop/VillageArt.fs b/src/LivingVillage.Desktop/VillageArt.fs
new file mode 100644
index 0000000..0be4786
--- /dev/null
+++ b/src/LivingVillage.Desktop/VillageArt.fs
@@ -0,0 +1,95 @@
+namespace LivingVillage.Desktop
+
+open LivingVillage.Kernel.Sim
+open LivingVillage.Desktop.VillagePresentation
+
+module VillageArt =
+
+    type PropKind =
+        | WhiteWallDarkTileHouse
+        | StoneBridge
+        | Bamboo
+        | VegetableGarden
+
+    type TileKind =
+        | RiverWater
+        | StonePaving
+
+    type ArtProp =
+        { Kind: PropKind
+          Position: TilePosition }
+
+    type ArtTile =
+        { Kind: TileKind
+          Position: TilePosition }
+
+    type JiangnanArtPlan =
+        { Props: ArtProp list
+          Tiles: ArtTile list }
+
+    type NpcVisualVariant =
+        | IndigoRobe
+        | OchreVest
+        | JadeSash
+
+    type FacingDirection =
+        | NorthFacing
+        | SouthFacing
+        | WestFacing
+        | EastFacing
+
+    type AnimationFrame =
+        | FrameOne
+        | FrameTwo
+
+    type NpcSpriteSpec =
+        { Variant: NpcVisualVariant
+          Direction: FacingDirection
+          Frame: AnimationFrame }
+
+    let private position x y : TilePosition =
+        { X = x
+          Y = y }
+
+    let private prop kind x y : ArtProp =
+        { Kind = kind
+          Position = position x y }
+
+    let private tile kind x y : ArtTile =
+        { Kind = kind
+          Position = position x y }
+
+    let samplePlan () : JiangnanArtPlan =
+        { Props =
+            [ prop WhiteWallDarkTileHouse 6 4
+              prop StoneBridge 10 4
+              prop Bamboo 3 2
+              prop VegetableGarden 8 7 ]
+          Tiles =
+            [ tile RiverWater 10 2
+              tile RiverWater 10 3
+              tile StonePaving 4 5
+              tile StonePaving 5 5
+              tile StonePaving 6 5 ] }
+
+    let private positiveModulo divisor value =
+        let remainder = value % divisor
+        if remainder < 0 then remainder + divisor else remainder
+
+    let npcVisualVariant (NpcId npcId) : NpcVisualVariant =
+        match positiveModulo 3 npcId with
+        | 0 -> IndigoRobe
+        | 1 -> OchreVest
+        | _ -> JadeSash
+
+    let private positiveModulo64 divisor value =
+        let remainder = value % divisor
+        if remainder < 0L then remainder + divisor else remainder
+
+    let animationFrame (tick: int64) : AnimationFrame =
+        if positiveModulo64 8L tick < 4L then FrameOne else FrameTwo
+
+    let npcSpriteSpec (npcId: NpcId) (direction: FacingDirection) (tick: int64) : NpcSpriteSpec =
+        { Variant = npcVisualVariant npcId
+          Direction = direction
+          Frame = animationFrame tick }