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/phase_pools.py

@@ -18,7 +18,7 @@ from .sketch_solver import resolve_required_sketches
 
 P3_ATOMIC_IDS = frozenset({
     "reference_plane", "reference_axis", "extrude_add_blind", "extrude_add_two_sided",
-    "extrude_cut_blind", "revolve_add", "revolve_cut",
+    "extrude_cut_blind", "extrude_cut_two_sided", "revolve_add", "revolve_cut",
 })
 P4_ATOMIC_IDS = P3_ATOMIC_IDS | frozenset({"hole_wizard"})
 P6_ATOMIC_IDS = P4_ATOMIC_IDS | frozenset({"pattern_linear", "pattern_mirror"})
@@ -27,7 +27,7 @@ P3_PROFILE_TYPES = frozenset({"analytic_contours", "circle", "polygon"})
 # revolve history.  Whether a first cut has a preceding active body remains a
 # runtime preflight question, not a reason to erase it from the input pool.
 _P3_PRIMARY_ATOMICS = frozenset({
-    "extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind", "revolve_add", "revolve_cut",
+    "extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind", "extrude_cut_two_sided", "revolve_add", "revolve_cut",
 })
 
 
@@ -47,8 +47,8 @@ def _p3_profile_ready(cdsl: dict[str, Any]) -> bool:
         if profile.get("type") not in P3_PROFILE_TYPES:
             return False
         if not (
-            any(len(region.get("outer") or []) >= 2 for region in sketch.get("contour_regions_mm") or () if isinstance(region, dict))
-            or len(sketch.get("contour_edges_mm") or ()) >= 2
+            any(len(region.get("outer") or []) >= 1 for region in sketch.get("contour_regions_mm") or () if isinstance(region, dict))
+            or len(sketch.get("contour_edges_mm") or ()) >= 1
             or any(
                 entity.get("type") == "circle" and not entity.get("construction") and float(entity.get("radius_mm") or 0.0) > 0
                 for entity in sketch.get("entities") or ()