给节点 offset 补上有限数值校验

src-tauri/src/ui_editor/persistence.rs 的 validate_node 现在校验 node.offset.min/max 必须是有限数值，与相邻的 Transform/custom_minimum_size 校验一致；此前只有 Transform 的 anchor/offset 被校验，NaN 或 Infinity 的树级偏移可以存盘，预览按 offset.min 定位时整棵树的渲染会一起失效

同文件新增 rejects_non_finite_node_offset，覆盖「offset 全有限可保存、min 变成 Infinity 后校验失败」

apps/ai-game-creator-shell/src-tauri/src/ui_editor/persistence.rs

@@ -710,6 +710,11 @@ fn validate_node(
     {
         return Err("UI 节点 Transform 必须是有限数值".to_string());
     }
+    if !node.offset.min.iter().all(|value| value.is_finite())
+        || !node.offset.max.iter().all(|value| value.is_finite())
+    {
+        return Err("UI 节点 offset 必须是有限数值".to_string());
+    }
     if node
         .layout
         .transform
@@ -1321,6 +1326,62 @@ mod tests {
         );
     }
 
+    #[test]
+    fn rejects_non_finite_node_offset() {
+        let state: State = serde_json::from_value(serde_json::json!({
+            "ui_trees": [{
+                "src_ui_design": "page",
+                "root": {
+                    "id": "root",
+                    "layout": {
+                        "transform": {
+                            "anchor_min": [0.0, 0.0],
+                            "anchor_max": [1.0, 1.0],
+                            "offset_min": [0.0, 0.0],
+                            "offset_max": [0.0, 0.0]
+                        },
+                        "custom_minimum_size": [0.0, 0.0],
+                        "size_flags_horizontal": 1,
+                        "size_flags_vertical": 1,
+                        "size_flags_stretch_ratio": 1.0,
+                        "container": "None"
+                    },
+                    "metadata": {
+                        "name": "根节点",
+                        "description": "",
+                        "layout_status": "NoProblem",
+                        "component_status": "NoProblem",
+                        "allow_llm_edit_layout": true,
+                        "allow_llm_edit_component": true,
+                        "source": "System"
+                    },
+                    "component": null,
+                    "children_display_mode": "Stack",
+                    "children": [],
+                    "offset": { "min": [0.0, 0.0], "max": [1280.0, 720.0] }
+                }
+            }],
+            "ui_design_images": {
+                "page": {
+                    "path": "missing.png",
+                    "pixel_size": [1280.0, 720.0],
+                    "pixels_per_unit": 1.0
+                }
+            },
+            "sprite_assets": {},
+            "font_assets": {}
+        }))
+        .expect("deserialize state with ordered offset");
+        assert_eq!(validate_state(&state), Ok(()));
+
+        let mut invalid = state;
+        invalid.ui_trees[0].root.offset.min[1] = f32::INFINITY;
+        assert_eq!(
+            validate_state(&invalid),
+            Err("UI 节点 offset 必须是有限数值".to_string())
+        );
+    }
+
     #[test]
     fn recovers_last_valid_state_when_primary_is_corrupt() {
         let (directory, asset_id) = fixture();