Add GIPHY image search feature

backend/handlers/api.go

@@ -33,6 +33,7 @@ type App struct {
 	WorkerScript    string
 	SearchService   *services.SearchService
 	GeminiService   *services.GeminiService
+	GiphyService    *services.GiphyService
 	Hub             *Hub
 }
 
@@ -149,6 +150,8 @@ func RegisterRoutes(router *gin.Engine, app *App) {
 	router.POST("/api/download", app.startDownload)
 	router.POST("/api/translate/summary", app.translateSummary)
 	router.POST("/api/search", app.searchMedia)
+	router.POST("/api/giphy/search", app.searchGiphy)
+	router.POST("/api/giphy/download", app.downloadGiphy)
 }
 
 func (a *App) debug(message string, data any) {