feat: 跨格式转换时按 ApiFamily 优先级排序端点

- 为 ApiFamily 枚举添加 priority 属性 (OpenAI=1, Claude=2, Gemini=3)
- 新增 _sort_endpoints_by_family_priority 函数按优先级排序端点
- 在调度器中对各分组内的端点应用优先级排序
- 修正测试文件的 type ignore 注解 (attr-defined -> method-assign)
- 新增 7 个端点排序相关的单元测试

src/core/api_format/enums.py

@@ -17,6 +17,15 @@ class ApiFamily(str, Enum):
     CLAUDE = "claude"  # claude-compatible
     GEMINI = "gemini"  # gemini-compatible
 
+    @property
+    def priority(self) -> int:
+        """基础优先级（数字越小越优先）"""
+        return {
+            ApiFamily.OPENAI: 1,
+            ApiFamily.CLAUDE: 2,
+            ApiFamily.GEMINI: 3,
+        }.get(self, 99)
+
 
 class EndpointKind(str, Enum):
     """

src/services/cache/aware_scheduler.py

@@ -34,12 +34,13 @@ import hashlib
 import random
 import re
 import time
+from collections.abc import Sequence
 from dataclasses import dataclass
 from typing import TYPE_CHECKING, Any
 
 from sqlalchemy.orm import Session, selectinload
 
-from src.core.api_format.enums import EndpointKind
+from src.core.api_format.enums import ApiFamily, EndpointKind
 from src.core.api_format.signature import make_signature_key, parse_signature_key
 from src.core.exceptions import ModelNotSupportedException, ProviderNotAvailableException
 from src.core.logger import logger
@@ -103,6 +104,21 @@ class ConcurrencySnapshot:
         )
 
 
+def _sort_endpoints_by_family_priority(
+    eps: Sequence[ProviderEndpoint],
+) -> list[ProviderEndpoint]:
+    """按 ApiFamily 优先级对端点排序（同分组内使用）。"""
+
+    def sort_key(ep: ProviderEndpoint) -> int:
+        family_str = str(getattr(ep, "api_family", "") or "").strip().lower()
+        try:
+            return ApiFamily(family_str).priority
+        except ValueError:
+            return 99
+
+    return sorted(eps, key=sort_key)
+
+
 class CacheAwareScheduler:
     """
     缓存感知调度器
@@ -1149,7 +1165,12 @@ class CacheAwareScheduler:
                 else:
                     fallback_other_family.append(ep)
 
-            endpoints = preferred + preferred_other_family + fallback + fallback_other_family
+            endpoints = (
+                _sort_endpoints_by_family_priority(preferred)
+                + _sort_endpoints_by_family_priority(preferred_other_family)
+                + _sort_endpoints_by_family_priority(fallback)
+                + _sort_endpoints_by_family_priority(fallback_other_family)
+            )
 
             for endpoint in endpoints:
                 logger.debug(