feat: update API routes for multiple folder support

- Add routes for ebook folder management in auth group
- Add routes for scanner operations (scan, start, stop)
- Update route handlers to use new multiple folder endpoints
- Maintain JWT authentication for protected routes

backend/cmd/server/main.go

@@ -81,6 +81,9 @@ func main() {
 	// Protected routes
 	protected := e.Group("/api", jwtMiddleware)
 	protected.GET("/auth/profile", auth.GetProfile)
+	protected.POST("/auth/ebook-folders", auth.AddEbookFolder)
+	protected.GET("/auth/ebook-folders", auth.GetEbookFolders)
+	protected.DELETE("/auth/ebook-folders/:folderPath", auth.DeleteEbookFolder)
 	protected.GET("/users", auth.ListUsers)
 
 	// Routes