refactor(moldinsight): 引入可插拔注册表（MoldGenerator + FeatureDetector）

- 新增 MoldGeneratorRegistry：multi_scheme_planner 消除 if-else，按 mold_type 选生成器
- 新增 FeatureDetectorRegistry：geometry_analyzer._detect_features 消除 6 个检测器硬编码
- 新增模具类型/特征检测器只需 register 一行
- 移除 OCC ThreadPoolExecutor（注册表本身串行执行）

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

src/moldinsight/core/multi_scheme_planner.py

@@ -8,8 +8,7 @@ from OCC.Core.TopAbs import TopAbs_FACE
 from OCC.Core.TopExp import TopExp_Explorer
 from OCC.Core.TopoDS import TopoDS_Face, TopoDS_Shape, topods
 
-from moldinsight.core.mold_generator import MoldCavityGenerator
-from moldinsight.core.aluminum_foam_mold import AluminumFoamMoldGenerator
+from moldinsight.core.mold_generator_registry import mold_generator_registry
 from moldinsight.core.parting_candidate_generator import PartingCandidateGenerator
 from moldinsight.core.parting_scheme_scorer import PartingSchemeScorer
 from shared.utils.logger import get_logger
@@ -23,11 +22,6 @@ class MultiSchemeMoldPlanner:
     def __init__(self):
         self.candidate_generator = PartingCandidateGenerator()
         self.scheme_scorer = PartingSchemeScorer()
-        self.mold_generator = MoldCavityGenerator(shrinkage_rate=0.005)
-        self.aluminum_foam_generator = AluminumFoamMoldGenerator(
-            shrinkage_rate=0.015,
-            draft_angle=3.0,
-        )
 
     def generate_plan(
         self,
@@ -37,7 +31,7 @@ class MultiSchemeMoldPlanner:
         max_schemes: int = 3,
         process_params: Optional[Dict[str, Any]] = None,
     ) -> Dict[str, Any]:
-        generator = self.aluminum_foam_generator if is_foam_material else self.mold_generator
+        generator = mold_generator_registry.get_by_type("aluminum_foam" if is_foam_material else "injection")
         generator.set_material(material["name"])
         self._apply_process_params(generator, material, process_params)