[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

src/owner_voice_pet/cli.py

@@ -21,6 +21,7 @@ from .wakeword import KeywordWakeWordProvider
 
 def main(argv: list[str] | None = None) -> int:
     parser = argparse.ArgumentParser(prog="owner-voice-pet")
+    parser.add_argument("--env-file", default=".env", help="Path to .env config file")
     parser.add_argument("--show-config", action="store_true", help="Print non-secret config summary")
     subparsers = parser.add_subparsers(dest="command")
     subparsers.add_parser("acceptance", help="Run deterministic end-to-end pipeline acceptance")
@@ -32,7 +33,7 @@ def main(argv: list[str] | None = None) -> int:
     args = parser.parse_args(argv)
 
     if args.show_config:
-        config = AppConfig.from_env()
+        config = AppConfig.from_dotenv(args.env_file)
         print(
             json.dumps(
                 {
@@ -53,7 +54,7 @@ def main(argv: list[str] | None = None) -> int:
         return 0
 
     if args.command == "validate-assets":
-        infos = validate_pet_assets(AppConfig.from_env().asset_dir)
+        infos = validate_pet_assets(AppConfig.from_dotenv(args.env_file).asset_dir)
         print(json.dumps({"assets": len(infos), "valid": True}, ensure_ascii=False, sort_keys=True))
         return 0
 
@@ -68,7 +69,7 @@ def main(argv: list[str] | None = None) -> int:
         return 0 if result["success"] else 1
 
     if args.command == "llm-smoke":
-        config = AppConfig.from_env()
+        config = AppConfig.from_dotenv(args.env_file)
         if args.no_stream:
             config = AppConfig(
                 wake_word=config.wake_word,
@@ -102,7 +103,7 @@ def main(argv: list[str] | None = None) -> int:
 
 
 def run_acceptance() -> dict[str, object]:
-    validate_pet_assets(AppConfig.from_env().asset_dir)
+    validate_pet_assets(AppConfig.from_dotenv().asset_dir)
     frames = [
         AudioFrame(b"\x80\x80", 16000, 1, 0, 0, {"duration_ms": 20, "wake_word": "小杰小杰", "wake_confidence": 0.99}),
         AudioFrame(b"\xff\xff", 16000, 1, 20, 1, {"duration_ms": 20, "speech": True, "transcript": "你是谁"}),