Improve the loading indicator for the new item page previews

Add some unobtrusive white background for contrast, show it when the
Turbo frame is loading too, add a spinner cursor, and fix a silliness
of how we put the `position: absolute` stuff into the component-y part
of the hanger spinner instead of this specific use case lol oops!

app/assets/stylesheets/application/hanger-spinner.css

@@ -1,8 +1,4 @@
 .hanger-spinner {
-	position: absolute;
-	bottom: 8px;
-	right: 12px;
-
 	height: 32px;
 	width: 32px;
 

app/assets/stylesheets/items/_show.sass

@@ -58,20 +58,37 @@ body.items-show
         width: 100%
         height: 100%
 
-    .hanger-spinner
+    .loading-indicator
+      position: absolute
+      z-index: 999
+      bottom: 0px
+      right: 4px
+      padding: 8px
+      background: radial-gradient(circle closest-side, white 45%, #ffffff00)
+
       opacity: 0
       transition: opacity .5s
 
     // When loading, fade in the loading spinner after a brief delay. (We only
     // apply the delay here, because fading *out* on load should be instant.)
     &:has(outfit-layer:state(loading))
-      .hanger-spinner
+      cursor: wait
+      .loading-indicator
         opacity: 1
         transition-delay: 2s
 
     &:has(outfit-layer:state(error))
       border-color: $error-border-color
 
+  // We also show the loading spinner when the item preview Turbo frame is
+  // loading in new data for us.
+  turbo-frame#item-preview[busy]
+    .outfit-viewer
+      cursor: wait
+    .loading-indicator
+      opacity: 1
+      transition-delay: 2s
+
   .species-color-picker
     .error-icon
       cursor: help

app/views/items/_outfit_viewer.html.haml

@@ -1,5 +1,5 @@
 .outfit-viewer
-  = render partial: "hanger_spinner"
+  .loading-indicator= render partial: "hanger_spinner"
   - outfit.visible_layers.each do |swf_asset|
     %outfit-layer{
       data: {