[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/config.py

@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-import os
 from dataclasses import dataclass
 from pathlib import Path
 
@@ -25,9 +24,11 @@ class AppConfig:
     context_max_chars: int = 12000
 
     @classmethod
-    def from_env(cls, prefix: str = "OWNER_") -> "AppConfig":
+    def from_dotenv(cls, path: str | Path = ".env", prefix: str = "OWNER_") -> "AppConfig":
+        values = parse_dotenv(Path(path))
+
         def get(name: str, default: str | None = None) -> str | None:
-            value = os.environ.get(f"{prefix}{name}")
+            value = values.get(f"{prefix}{name}")
             return default if value is None or value == "" else value
 
         return cls(
@@ -47,6 +48,10 @@ class AppConfig:
             context_max_chars=int(get("CONTEXT_MAX_CHARS", "12000") or "12000"),
         )
 
+    @classmethod
+    def from_env(cls, prefix: str = "OWNER_") -> "AppConfig":
+        return cls.from_dotenv(".env", prefix=prefix)
+
     def require_llm_credentials(self) -> None:
         if not self.llm_api_key:
             raise ProviderError(
@@ -100,3 +105,32 @@ class AppConfig:
                 )
             )
         return errors
+
+
+def parse_dotenv(path: Path) -> dict[str, str]:
+    if not path.exists():
+        return {}
+    values: dict[str, str] = {}
+    for line_no, raw_line in enumerate(path.read_text(encoding="utf-8").splitlines(), start=1):
+        line = raw_line.strip()
+        if not line or line.startswith("#"):
+            continue
+        if line.startswith("export "):
+            line = line.removeprefix("export ").strip()
+        if "=" not in line:
+            raise ValueError(f"invalid .env line {line_no}: missing '='")
+        key, value = line.split("=", 1)
+        key = key.strip()
+        value = _strip_dotenv_value(value.strip())
+        if not key:
+            raise ValueError(f"invalid .env line {line_no}: empty key")
+        values[key] = value
+    return values
+
+
+def _strip_dotenv_value(value: str) -> str:
+    if len(value) >= 2 and value[0] == value[-1] and value[0] in {"'", '"'}:
+        return value[1:-1]
+    if " #" in value:
+        return value.split(" #", 1)[0].rstrip()
+    return value