feat: complete remaining Go backend modules

backend/cmd/zhinian-api/main.go

@@ -14,6 +14,7 @@ import (
 	"time"
 
 	"git.nianxx.cn/wangxuming/NianAIGC/backend/internal/application"
+	"git.nianxx.cn/wangxuming/NianAIGC/backend/internal/settings"
 )
 
 const shutdownTimeout = 10 * time.Second
@@ -28,14 +29,18 @@ func run() error {
 	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
 	defer stop()
 
-	app, err := application.New(application.Options{Context: ctx})
+	getenv, err := runtimeGetenv(os.Getenv)
+	if err != nil {
+		return fmt.Errorf("load Go backend runtime settings: %w", err)
+	}
+	app, err := application.New(application.Options{Context: ctx, Getenv: getenv})
 	if err != nil {
 		return fmt.Errorf("initialize Go backend: %w", err)
 	}
 	defer app.Close()
 
 	server := &http.Server{
-		Addr:              listenAddress(os.Getenv),
+		Addr:              listenAddress(getenv),
 		Handler:           app.Handler(),
 		ReadHeaderTimeout: 5 * time.Second,
 	}
@@ -66,6 +71,29 @@ func run() error {
 	return nil
 }
 
+func runtimeGetenv(process func(string) string) (func(string) string, error) {
+	path := strings.TrimSpace(process("ZHINIAN_SETTINGS_FILE"))
+	if path == "" {
+		path = ".env.local"
+	}
+	values := map[string]string{}
+	for _, key := range settings.RuntimeSettingKeys() {
+		if value := process(key); value != "" {
+			values[key] = value
+		}
+	}
+	merged, err := settings.LoadEnvironment(path, values)
+	if err != nil {
+		return nil, err
+	}
+	return func(name string) string {
+		if value, exists := merged[name]; exists {
+			return value
+		}
+		return process(name)
+	}, nil
+}
+
 func listenAddress(getenv func(string) string) string {
 	host := strings.TrimSpace(getenv("GO_BACKEND_HOST"))
 	if host == "" {