fix(providers): 允许 max_probe_interval_minutes 设为 0 并修复零值被覆盖的问题

- 将 max_probe_interval_minutes 校验范围从 2-32 改为 0-32
- 修复 routes.py 中 max_probe_interval_minutes 和 cache_ttl_minutes
  使用 `or` 短路导致零值被默认值覆盖的问题，改用 is not None 判断
- 前端表单同步调整最小值约束和提示文案
- 新增零值校验的单元测试

tests/services/test_provider_keys_key_command_service.py

@@ -9,7 +9,7 @@ from typing import Any, cast
 import pytest
 
 from src.core.exceptions import InvalidRequestException
-from src.models.endpoint_models import EndpointAPIKeyUpdate
+from src.models.endpoint_models import EndpointAPIKeyCreate, EndpointAPIKeyUpdate
 
 
 async def _noop_invalidate_models_list_cache() -> None:
@@ -72,6 +72,25 @@ def _build_key(**overrides: Any) -> SimpleNamespace:
     return SimpleNamespace(**base)
 
 
+def test_key_create_accepts_zero_max_probe_interval_minutes() -> None:
+    payload = EndpointAPIKeyCreate.model_validate(
+        {
+            "name": "key-1",
+            "api_key": "secret",
+            "api_formats": ["openai:chat"],
+            "max_probe_interval_minutes": 0,
+        }
+    )
+
+    assert payload.max_probe_interval_minutes == 0
+
+
+def test_key_update_accepts_zero_max_probe_interval_minutes() -> None:
+    payload = EndpointAPIKeyUpdate.model_validate({"max_probe_interval_minutes": 0})
+
+    assert payload.max_probe_interval_minutes == 0
+
+
 def test_prepare_update_payload_auth_type_null_ignored() -> None:
     key = _build_key(auth_type="api_key")
     key_data = EndpointAPIKeyUpdate.model_validate({"auth_type": None})