feat(cadfs): 补齐核心建模能力并建立代表性回归

- 新增 loft、双向切除、through-all/up-to-next 等 CADFS lowering 与 engine 支持
- 支持多种 reference plane、B-spline profile 和 circular pattern replay
- 保留 transform 历史，并烘焙安全的单源平移/旋转变换
- 改进 selector 绑定、拓扑快照和 pattern 变换处理
- 建立 17 个代表样本的转换、重建与比较回归工具链
- 补充 schema、author guidance、运行时和几何回归测试

backend/engine/cdsl_engine/cdsl_schema.json

@@ -108,6 +108,20 @@
       "required": ["end_condition"],
       "additionalProperties": false
     },
+    "loftParams": {
+      "type": "object",
+      "properties": {
+        "profile_sketch_ids": {
+          "type": "array",
+          "minItems": 2,
+          "maxItems": 16,
+          "uniqueItems": true,
+          "items": {"type": "string", "pattern": "^[A-Za-z0-9_-]{1,80}$"}
+        }
+      },
+      "required": ["profile_sketch_ids"],
+      "additionalProperties": false
+    },
     "revolveParams": {
       "type": "object",
       "properties": {"angle_deg": {"type": "number", "minimum": 0, "maximum": 360}, "axis": {"$ref": "#/$defs/axis"}, "reverse": {"type": "boolean"}, "end_condition": {"$ref": "#/$defs/endCondition"}},
@@ -335,18 +349,20 @@
     "analyticSegment": {
       "type": "object",
       "properties": {
-        "type": {"enum": ["line", "arc", "circle"]},
+        "type": {"enum": ["line", "arc", "circle", "bspline"]},
         "start": {"$ref": "#/$defs/point2"},
         "end": {"$ref": "#/$defs/point2"},
         "center": {"$ref": "#/$defs/point2"},
         "radius_mm": {"$ref": "#/$defs/positive"},
+        "points": {"type": "array", "minItems": 3, "items": {"$ref": "#/$defs/point2"}},
         "clockwise": {"type": "boolean"}
       },
       "required": ["type"],
       "allOf": [
         {"if": {"properties": {"type": {"const": "line"}}}, "then": {"required": ["start", "end"]}},
         {"if": {"properties": {"type": {"const": "arc"}}}, "then": {"required": ["start", "end", "center", "radius_mm"]}},
-        {"if": {"properties": {"type": {"const": "circle"}}}, "then": {"required": ["center", "radius_mm"]}}
+        {"if": {"properties": {"type": {"const": "circle"}}}, "then": {"required": ["center", "radius_mm"]}},
+        {"if": {"properties": {"type": {"const": "bspline"}}}, "then": {"required": ["start", "end", "points"]}}
       ],
       "additionalProperties": false
     },
@@ -389,7 +405,7 @@
       "required": ["type", "contours"],
       "additionalProperties": false
     },
-    "feature_atomic_ids": {"enum": ["extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind", "extrude_cut_through", "revolve_add", "revolve_cut", "hole_blind", "hole_countersink", "hole_counterbore", "sphere_add", "box_add", "cylinder_add", "thread_add", "thread_cut", "fillet", "chamfer", "pattern_linear", "pattern_mirror", "pattern_circular", "reference_plane", "reference_axis", "hole_wizard"]},
+    "feature_atomic_ids": {"enum": ["extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind", "extrude_cut_two_sided", "extrude_cut_through", "loft_add", "revolve_add", "revolve_cut", "hole_blind", "hole_countersink", "hole_counterbore", "sphere_add", "box_add", "cylinder_add", "thread_add", "thread_cut", "fillet", "chamfer", "pattern_linear", "pattern_mirror", "pattern_circular", "reference_plane", "reference_axis", "hole_wizard"]},
     "feature": {
       "type": "object",
       "properties": {
@@ -410,6 +426,8 @@
         {"if": {"properties": {"atomic_id": {"const": "extrude_add_two_sided"}}}, "then": {"properties": {"params": {"$ref": "#/$defs/extrudeParams"}}}},
         {"if": {"properties": {"atomic_id": {"const": "extrude_cut_blind"}}}, "then": {"properties": {"params": {"$ref": "#/$defs/extrudeParams"}}}},
         {"if": {"properties": {"atomic_id": {"const": "extrude_cut_through"}}}, "then": {"properties": {"params": {"$ref": "#/$defs/extrudeCutThroughParams"}}}},
+        {"if": {"properties": {"atomic_id": {"const": "extrude_cut_two_sided"}}}, "then": {"properties": {"params": {"$ref": "#/$defs/extrudeParams"}}}},
+        {"if": {"properties": {"atomic_id": {"const": "loft_add"}}}, "then": {"properties": {"params": {"$ref": "#/$defs/loftParams"}}}},
         {"if": {"properties": {"atomic_id": {"const": "revolve_add"}}}, "then": {"properties": {"params": {"$ref": "#/$defs/revolveParams"}}}},
         {"if": {"properties": {"atomic_id": {"const": "revolve_cut"}}}, "then": {"properties": {"params": {"$ref": "#/$defs/revolveParams"}}}},
         {"if": {"properties": {"atomic_id": {"const": "sphere_add"}}}, "then": {"properties": {"params": {"$ref": "#/$defs/sphereParams"}}}},