feat(config): 配置加载与 schema 校验（.env/env 注入 + 反射解码 + 校验）

internal/config/dotenv.go

@@ -0,0 +1,39 @@
+package config
+
+import (
+	"os"
+	"strings"
+)
+
+// parseDotEnv loads a KEY=VALUE .env file into a map. It is tolerant by design:
+// a missing file yields an empty map and no error, because .env is a
+// development-only convenience. Values may be single- or double-quoted and may
+// carry an optional `export` prefix. Lines starting with `#` and blank lines
+// are ignored.
+func parseDotEnv(path string) (map[string]string, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return map[string]string{}, nil
+		}
+		return nil, err
+	}
+
+	env := make(map[string]string)
+	for _, raw := range strings.Split(string(data), "\n") {
+		line := strings.TrimSpace(raw)
+		if line == "" || strings.HasPrefix(line, "#") {
+			continue
+		}
+		line = strings.TrimPrefix(line, "export ")
+		key, val, ok := strings.Cut(line, "=")
+		if !ok {
+			continue
+		}
+		key = strings.TrimSpace(key)
+		val = strings.TrimSpace(val)
+		val = strings.Trim(val, `"'`)
+		env[key] = val
+	}
+	return env, nil
+}