feat: initial FRED API Proxy project

- Go web server using Gin framework
- Proxy FRED economic data API
- Support series, observations, search, releases endpoints

config/config.go

@@ -0,0 +1,34 @@
+package config
+
+import (
+	"os"
+)
+
+type Config struct {
+	FREDAPIKey  string
+	ServerPort  string
+	FREDBaseURL string
+}
+
+func Load() *Config {
+	apiKey := os.Getenv("FRED_API_KEY")
+	if apiKey == "" {
+		apiKey = "987b9c3428a3d0fe90179e3e6298d05e"
+	}
+
+	port := os.Getenv("SERVER_PORT")
+	if port == "" {
+		port = "8080"
+	}
+
+	baseURL := os.Getenv("FRED_BASE_URL")
+	if baseURL == "" {
+		baseURL = "https://api.stlouisfed.org/fred"
+	}
+
+	return &Config{
+		FREDAPIKey:  apiKey,
+		ServerPort:  port,
+		FREDBaseURL: baseURL,
+	}
+}