feat(M0): 工程地基 - Go API + Python 采集骨架 + CI + 数据契约

- api/: Go(chi) 只读 API 骨架, /healthz + 版本化路由(占位), Dockerfile, 单测
- ingestion/: Python 采集/ETL 包骨架, units 单位归一化(纯函数+测试), adapter 协议
- docker-compose.yml: postgres + redis + minio + api
- .github/workflows/ci.yml: Go build/vet/test + Python ruff/pytest
- docs/data-contract.md(两端共享契约) + docs/disclaimer.md(不提供购买声明)
- migrations/ 占位(M1 起填充)

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

api/internal/config/config.go

@@ -0,0 +1,30 @@
+package config
+
+import (
+	"os"
+)
+
+// Config holds runtime configuration for the OpenGoods API server.
+// Values are read from environment variables with sensible defaults so the
+// server can boot in a local Docker Compose setup without extra configuration.
+type Config struct {
+	Addr        string
+	DatabaseURL string
+	RedisURL    string
+}
+
+// Load reads configuration from the environment.
+func Load() Config {
+	return Config{
+		Addr:        getenv("OPENGOODS_ADDR", ":8080"),
+		DatabaseURL: getenv("OPENGOODS_DATABASE_URL", "postgres://opengoods:opengoods@localhost:5432/opengoods?sslmode=disable"),
+		RedisURL:    getenv("OPENGOODS_REDIS_URL", "redis://localhost:6379/0"),
+	}
+}
+
+func getenv(key, fallback string) string {
+	if v, ok := os.LookupEnv(key); ok && v != "" {
+		return v
+	}
+	return fallback
+}