Pack Textures/ into atlases and render the world from them

Engine bump brings MrGameEng.Atlases (atlas builder + runtime loader).
Textures/ (2747 images) is packed by MrGameEng.AtlasTool into 10 atlases
(93 pages) under Assets/Atlases, loaded through generated handles.
Beings now draw pawn bodies, forest cells grow trees (both Y-sorted),
and the dev console gains 'atlas [name] [filter]' for inspection.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

CLAUDE.md

@@ -25,6 +25,19 @@ dotnet run --project src/LittleSim -c Release   # measure perf in Release only
 dotnet test LittleSim.sln                        # runs the engine test suites
 ```
 
+## Texture atlases
+
+Source images live in `Textures/` (committed); the game only loads packed atlases from
+`src/LittleSim/Assets/Atlases` (also committed — the asset generator emits
+`GameAssets.Atlases.*` handles for them). After changing `Textures/`, rebuild with:
+
+```
+dotnet run --project engine/tools/MrGameEng.AtlasTool -c Release -- Textures src/LittleSim/Assets/Atlases --group-depth 2
+```
+
+Rebuilds are incremental (unchanged groups are skipped). Region keys are paths relative
+to `Textures/` without extension: `atlas.GetRegion("Things/Plant/TreeOak/TreeOakA")`.
+
 ## Submodule workflow
 
 Engine changes are committed **inside `engine/` first** (engine repo, its commit style),

src/LittleSim/Assets/Atlases/Terrain.Surfaces.atlas

@@ -0,0 +1,31 @@
+{
+  "version": 1,
+  "name": "Terrain.Surfaces",
+  "pageSize": 2048,
+  "padding": 2,
+  "pages": [
+    {
+      "file": "Terrain.Surfaces.atlas.0.png",
+      "width": 256,
+      "height": 128
+    }
+  ],
+  "regions": [
+    {
+      "key": "Terrain/Surfaces/Marsh",
+      "page": 0,
+      "x": 2,
+      "y": 2,
+      "w": 64,
+      "h": 64
+    },
+    {
+      "key": "Terrain/Surfaces/Marsh_bright",
+      "page": 0,
+      "x": 68,
+      "y": 2,
+      "w": 64,
+      "h": 64
+    }
+  ]
+}

src/LittleSim/Assets/Atlases/Things.World.atlas

@@ -0,0 +1,63 @@
+{
+  "version": 1,
+  "name": "Things.World",
+  "pageSize": 2048,
+  "padding": 2,
+  "pages": [
+    {
+      "file": "Things.World.atlas.0.png",
+      "width": 1024,
+      "height": 256
+    }
+  ],
+  "regions": [
+    {
+      "key": "Things/World/WorldObjects/Expanding/PirateOutpost",
+      "page": 0,
+      "x": 2,
+      "y": 2,
+      "w": 128,
+      "h": 128
+    },
+    {
+      "key": "Things/World/WorldObjects/Expanding/Town",
+      "page": 0,
+      "x": 132,
+      "y": 2,
+      "w": 128,
+      "h": 128
+    },
+    {
+      "key": "Things/World/WorldObjects/Expanding/TownRough",
+      "page": 0,
+      "x": 262,
+      "y": 2,
+      "w": 128,
+      "h": 128
+    },
+    {
+      "key": "Things/World/WorldObjects/Expanding/Village",
+      "page": 0,
+      "x": 392,
+      "y": 2,
+      "w": 128,
+      "h": 128
+    },
+    {
+      "key": "Things/World/WorldObjects/Expanding/VillageRough",
+      "page": 0,
+      "x": 522,
+      "y": 2,
+      "w": 128,
+      "h": 128
+    },
+    {
+      "key": "Things/World/WorldObjects/Expanding/VillageSavage",
+      "page": 0,
+      "x": 652,
+      "y": 2,
+      "w": 128,
+      "h": 128
+    }
+  ]
+}

src/LittleSim/Assets/Atlases/UI.Buttons.atlas

@@ -0,0 +1,127 @@
+{
+  "version": 1,
+  "name": "UI.Buttons",
+  "pageSize": 2048,
+  "padding": 2,
+  "pages": [
+    {
+      "file": "UI.Buttons.atlas.0.png",
+      "width": 1024,
+      "height": 128
+    }
+  ],
+  "regions": [
+    {
+      "key": "UI/Buttons/MainButtons/IconAnimals",
+      "page": 0,
+      "x": 2,
+      "y": 2,
+      "w": 64,
+      "h": 64
+    },
+    {
+      "key": "UI/Buttons/MainButtons/IconArchitect",
+      "page": 0,
+      "x": 68,
+      "y": 2,
+      "w": 64,
+      "h": 64
+    },
+    {
+      "key": "UI/Buttons/MainButtons/IconAssign",
+      "page": 0,
+      "x": 134,
+      "y": 2,
+      "w": 64,
+      "h": 64
+    },
+    {
+      "key": "UI/Buttons/MainButtons/IconFactions",
+      "page": 0,
+      "x": 200,
+      "y": 2,
+      "w": 64,
+      "h": 64
+    },
+    {
+      "key": "UI/Buttons/MainButtons/IconHistory",
+      "page": 0,
+      "x": 266,
+      "y": 2,
+      "w": 64,
+      "h": 64
+    },
+    {
+      "key": "UI/Buttons/MainButtons/IconMechanoids",
+      "page": 0,
+      "x": 332,
+      "y": 2,
+      "w": 64,
+      "h": 64
+    },
+    {
+      "key": "UI/Buttons/MainButtons/IconMenu",
+      "page": 0,
+      "x": 398,
+      "y": 2,
+      "w": 64,
+      "h": 64
+    },
+    {
+      "key": "UI/Buttons/MainButtons/IconQuests",
+      "page": 0,
+      "x": 464,
+      "y": 2,
+      "w": 64,
+      "h": 64
+    },
+    {
+      "key": "UI/Buttons/MainButtons/IconResearch",
+      "page": 0,
+      "x": 530,
+      "y": 2,
+      "w": 64,
+      "h": 64
+    },
+    {
+      "key": "UI/Buttons/MainButtons/IconRestrict",
+      "page": 0,
+      "x": 596,
+      "y": 2,
+      "w": 64,
+      "h": 64
+    },
+    {
+      "key": "UI/Buttons/MainButtons/IconSchedule",
+      "page": 0,
+      "x": 662,
+      "y": 2,
+      "w": 64,
+      "h": 64
+    },
+    {
+      "key": "UI/Buttons/MainButtons/IconWildlife",
+      "page": 0,
+      "x": 728,
+      "y": 2,
+      "w": 64,
+      "h": 64
+    },
+    {
+      "key": "UI/Buttons/MainButtons/IconWork",
+      "page": 0,
+      "x": 794,
+      "y": 2,
+      "w": 64,
+      "h": 64
+    },
+    {
+      "key": "UI/Buttons/MainButtons/IconWorld",
+      "page": 0,
+      "x": 860,
+      "y": 2,
+      "w": 64,
+      "h": 64
+    }
+  ]
+}

src/LittleSim/Assets/Atlases/UI.Overlays.atlas

@@ -0,0 +1,23 @@
+{
+  "version": 1,
+  "name": "UI.Overlays",
+  "pageSize": 2048,
+  "padding": 2,
+  "pages": [
+    {
+      "file": "UI.Overlays.atlas.0.png",
+      "width": 256,
+      "height": 256
+    }
+  ],
+  "regions": [
+    {
+      "key": "UI/Overlays/NeedsPower",
+      "page": 0,
+      "x": 2,
+      "y": 2,
+      "w": 128,
+      "h": 128
+    }
+  ]
+}