[配置]：完成 .env 文件读取配置，包含自动加载、CLI 参数、测试覆盖和中文说明

tests/test_models_config.py

@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-import os
+import tempfile
 import unittest
 
 from owner_voice_pet.config import AppConfig
@@ -52,21 +52,30 @@ class ModelsConfigTests(unittest.TestCase):
         self.assertIn("LLM_API_KEY_MISSING", str(error))
         self.assertIn("llm/openai-compatible", str(error))
 
-    def test_config_from_env_masks_secret_boundary(self) -> None:
-        old_env = dict(os.environ)
-        try:
-            os.environ["OWNER_LLM_BASE_URL"] = "https://newapi.mkbk.shop/"
-            os.environ["OWNER_LLM_API_KEY"] = "secret-value"
-            os.environ["OWNER_LLM_MODEL"] = "test-model"
-            config = AppConfig.from_env()
+    def test_config_from_dotenv_uses_file_values(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            path = f"{tmp}/.env"
+            with open(path, "w", encoding="utf-8") as handle:
+                handle.write(
+                    "\n".join(
+                        [
+                            "OWNER_LLM_BASE_URL=https://newapi.mkbk.shop/",
+                            "OWNER_LLM_API_KEY=secret-value",
+                            "OWNER_LLM_MODEL=test-model",
+                        ]
+                    )
+                )
+            config = AppConfig.from_dotenv(path)
             self.assertEqual(config.llm_base_url, "https://newapi.mkbk.shop")
             self.assertEqual(config.llm_api_key, "secret-value")
             self.assertEqual(config.llm_model, "test-model")
             self.assertTrue(config.llm_stream)
             self.assertEqual(config.validate_basic(), [])
-        finally:
-            os.environ.clear()
-            os.environ.update(old_env)
+
+    def test_missing_dotenv_uses_non_secret_defaults(self) -> None:
+        config = AppConfig.from_dotenv("/tmp/owner-voice-pet-missing.env")
+        self.assertEqual(config.llm_base_url, "https://newapi.mkbk.shop")
+        self.assertIsNone(config.llm_api_key)
 
     def test_missing_llm_key_has_structured_error(self) -> None:
         config = AppConfig(llm_api_key=None)