Added /time endpoint for better sync experience

backend/internal/http/handlers.go

@@ -2,6 +2,7 @@ package httpapi
 
 import (
 	"net/http"
+	"time"
 
 	"watch-party-backend/internal/repo"
 	"watch-party-backend/internal/service"
@@ -17,6 +18,15 @@ func NewRouter(svc service.EpisodeService) *gin.Engine {
 		c.JSON(http.StatusOK, gin.H{"status": "ok"})
 	})
 
+	r.GET("/time", func(c *gin.Context) {
+		now := time.Now().UTC().UnixMilli()
+
+		c.Header("Cache-Control", "no-store, max-age=0, must-revalidate")
+		c.JSON(http.StatusOK, gin.H{
+			"now": now,
+		})
+	})
+
 	v1 := r.Group("/v1")
 
 	// GET /v1/current