Change encrypted URL format to /v1/e/{token}/img.{ext}

Add trailing filename to encrypted URLs for better browser compatibility.
The filename is ignored by the server but helps browsers identify content type.

internal/server/routes.go

@@ -56,7 +56,8 @@ func (s *Server) SetupRoutes() {
 	s.router.Head("/v1/image/*", s.h.HandleImage())
 
 	// Encrypted image URL route
-	s.router.Get("/v1/e/{token}", s.h.HandleImageEnc())
+	// The trailing filename (e.g., /img.jpg) is ignored but helps browsers with content type
+	s.router.Get("/v1/e/{token}/*", s.h.HandleImageEnc())
 
 	// Metrics endpoint with auth
 	if s.config.MetricsUsername != "" {