fix(moldinsight): 方案预览契约断裂——工艺参数面板全 N/A + 备选方案预览无法切换

多方案重构后 cavity_data 与可视化端字段契约断裂，两处收口：

- 契约桥接：CalculationService.attach_scheme_info_contract 把方案级
  key_info 内嵌回 cavity_data（mold_cavities.cavity_key_info / cavity_count /
  manufacturing_info 展示字段），multi_scheme_planner._build_scheme 生成后
  立即接线——3D 预览"关键工艺参数"面板此前 10 项 8 项恒 N/A，
  前端型腔数恒回退 1 腔
- 方案级预览恢复：_attach_scheme_previews 改为每方案生成完整预览
  （HTML + 摘要/数据 JSON 直传 RustFS）并写 scheme["html_file"]，
  前端切方案即切 iframe（此前仅最优方案一份，备选永远显示推荐预览）；
  删除零消费的 summary_file 死产物；任务级 HTML 复用推荐方案不再重复生成
- 前端 3D 预览标题栏加"当前：方案名"标识

已知取舍：报告键存储随方案数线性增长（记 TECH_DEBT D11 追记）；
历史任务不回填，需重新分析。接口面零变化，openapi 不重导出。

测试：193 passed, 13 skipped（净增契约桥接回归测试 1 项，OCC-free）；
vue-tsc 通过；本地无 pythonocc，planner 运行时路径待 conda 环境补跑。

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

tests/test_moldinsight_regressions.py

@@ -78,6 +78,52 @@ def test_calculation_service_attaches_injection_system_summary():
     assert "injection_system" in result
 
 
+def test_calculation_service_bridges_scheme_info_contract():
+    """多方案 cavity_data 必须自包含可视化面板依赖的 legacy 字段。
+
+    3D 预览"关键工艺参数"面板只拿得到 cavity_data；key_info 不内嵌回去则
+    面板整片 N/A、前端型腔数恒为 1（2026-09 事故根因）。
+    """
+    key_info = {
+        "mold_parameters": {
+            "shrinkage_rate": "0.50%",
+            "draft_angle": "2.0°",
+            "parting_line_length": 620.0,
+        },
+        "geometric_characteristics": {
+            "product_volume": "12.00 cm³",
+            "product_weight": "12.60 g",
+            "wall_thickness_range": "1.40 - 2.60 mm",
+        },
+        "manufacturing_requirements": {
+            "cavity_material": "P20钢材",
+            "hardness": "HRC 28-32",
+            "surface_finish": "SPI A2",
+            "estimated_cycle_time": "25 秒",
+        },
+    }
+    cavity_data = {
+        "metadata": {"shrinkage_rate": 0.005, "draft_angle": 2.0},
+        "manufacturing_info": {"recommended_material": "P20钢材"},
+        "mold_cavities": {"cavity": {"vertex_count": 1}, "core": {"vertex_count": 1}},
+    }
+
+    CalculationService.attach_scheme_info_contract(cavity_data, key_info)
+
+    mold_cavities = cavity_data["mold_cavities"]
+    assert mold_cavities["cavity_count"] == 1
+    assert (
+        mold_cavities["cavity_key_info"]["geometric_characteristics"]["product_volume"]
+        == "12.00 cm³"
+    )
+    manufacturing = cavity_data["manufacturing_info"]
+    assert manufacturing["mold_material"] == "P20钢材"
+    assert manufacturing["mold_hardness"] == "HRC 28-32"
+    assert manufacturing["surface_finish"] == "SPI A2"
+    assert manufacturing["estimated_cycle_time"] == "25 秒"
+    assert manufacturing["parting_line_length"] == 620.0
+
+
 def test_material_service_falls_back_to_abs_for_unknown_material():
     material = MaterialService.get_material("UNKNOWN")
     assert material["name"] == "ABS"