feat(infra): add OTel auto-instrumentations across all services

NestJS 6 services use getNodeAutoInstrumentations().

Python 2 services use FastAPIInstrumentor. Go 2 services use otelgin.

services/push-gateway/internal/config/config.go

@@ -4,19 +4,21 @@ import "os"
 
 // Config 持有 push-gateway 运行时配置
 type Config struct {
-	Port      string
-	JWTSecret string
-	DevMode   bool
-	RedisURL  string
+	Port         string
+	JWTSecret    string
+	DevMode      bool
+	RedisURL     string
+	OTLPEndpoint string
 }
 
 // Load 从环境变量加载配置并提供默认值
 func Load() *Config {
 	return &Config{
-		Port:      getEnv("PUSH_GATEWAY_PORT", "8081"),
-		JWTSecret: getEnv("JWT_SECRET", "p1-dev-secret-change-in-production"),
-		DevMode:   getEnv("DEV_MODE", "false") == "true",
-		RedisURL:  getEnv("REDIS_URL", ""),
+		Port:         getEnv("PUSH_GATEWAY_PORT", "8081"),
+		JWTSecret:    getEnv("JWT_SECRET", "p1-dev-secret-change-in-production"),
+		DevMode:      getEnv("DEV_MODE", "false") == "true",
+		RedisURL:     getEnv("REDIS_URL", ""),
+		OTLPEndpoint: getEnv("OTEL_EXPORTER_OTLP_ENDPOINT", "http://localhost:4318"),
 	}
 }