[ui] add fullscreen viewing for images

webui/src/components/display/blobs/ImageViewer.svelte

@@ -171,9 +171,19 @@
 
     imageLoaded = true;
   }
+
+  function clicked() {
+    if (!document.fullscreenElement) {
+      if (!editable) {
+        imageEl.requestFullscreen();
+      }
+    } else {
+      document.exitFullscreen();
+    }
+  }
 </script>
 
-<div class="image-viewer">
+<div class="image-viewer" class:editable on:click={clicked}>
   {#if !imageLoaded}
     <Spinner centered />
   {/if}
@@ -212,6 +222,14 @@
     .preview-image {
       margin: auto;
     }
+
+    &:not(.editable) {
+      cursor: zoom-in;
+    }
+
+    img:fullscreen {
+      cursor: zoom-out;
+    }
   }
 
   .r6o-editor {