fix(v2): 修复预审模型字段表三处缺陷并留出工具预算余量

- 补 8 个标准字段（还款来源/涉诉/增信/保证金/保险/客户名称），对齐原生方法文档声明的 inputs
- 字段守卫改为比对标准字段表，不再把"标准字段但本次无数据"误判为未知字段
- 向模型下发 standard_fields 并在提示词约束字段名，避免自造派生指标
- 补 insurance./deposit. 维度前缀；方案预算 12→18、120s→180s，版本升 1.1.0

实测（临时库 + DeepSeek）：模型类技能由 failed 转为 partial（部分 unknown 属如实标注），
降级记录为空，工具调用 11 次。字段表三处为代码层改动，对既有库即时生效。
验证：scripts/verify.py 11/11 PASS，531 项单测。

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

backend/services/assistant_materials.py

@@ -20,8 +20,16 @@ FIELDS = {
     "financial_assets": "financial.total_assets", "credit_overdue_count": "credit.overdue_count",
     "credit_report_date": "credit.report_date",
     "facility_term": "facility.term",
+    # 补齐原生方法文档声明、而 S1 字段表原本缺失的字段族：还款来源、涉诉、增信、保证金、保险、客户名称。
+    # 依据：skills/*/SKILL.md 的 inputs 声明，以及 REVIEW_TOPICS 已预设的 customer./repayment./legal./guarantee. 前缀。
+    "customer_name": "customer.name",
+    "repayment_source_type": "repayment.source_type", "repayment_annual_amount": "repayment.annual_amount",
+    "legal_case_count": "legal.case_count", "legal_amount": "legal.amount",
+    "guarantee_amount": "guarantee.amount", "deposit_amount": "deposit.amount",
+    "insurance_amount": "insurance.amount",
 }
-NUMERIC = set(FIELDS.values()) - {"collection.dependency", "collection.evidence", "credit.report_date"}
+NUMERIC = set(FIELDS.values()) - {"collection.dependency", "collection.evidence", "credit.report_date",
+                                  "customer.name", "repayment.source_type"}
 LIMIT = 10 * 1024 * 1024
 
 
@@ -30,7 +38,7 @@ def scalar(field, value):
         return None
     if field in NUMERIC:
         result = number(value)
-        if field in ("lease.duplicate_count", "credit.overdue_count") and (result < 0 or result != result.to_integral_value()):
+        if field in ("lease.duplicate_count", "credit.overdue_count", "legal.case_count") and (result < 0 or result != result.to_integral_value()):
             raise ValueError("数量必须为非负整数")
         if field in ("facility.amount", "lease.total_value") and result <= 0:
             raise ValueError("融资金额和租赁物价值必须为正数")