upload button tweaks

frontend/src/sidebar/Sidebar.jsx

@@ -563,20 +563,10 @@ const Sidebar = ({
         )}
         actions={(
           <>
-            <button
-              type="button"
-              className="icon-button"
-              onClick={handleUploadButtonClick}
-              disabled={!onUploadFiles || loading}
-              title="Upload documents"
-              aria-label="Upload documents"
-            >
-              <UploadIcon size={18} />
-            </button>
             {handleCollapse ? (
               <button
                 type="button"
-                className="icon-button"
+                className="icon-button sidebar__collapse-button"
                 onClick={handleCollapse}
                 aria-label="Collapse sidebar"
                 title="Collapse sidebar"
@@ -584,6 +574,16 @@ const Sidebar = ({
                 <SidebarCollapseIcon />
               </button>
             ) : null}
+            <button
+              type="button"
+              className="icon-button"
+              onClick={handleUploadButtonClick}
+              disabled={!onUploadFiles}
+              title="Upload documents"
+              aria-label="Upload documents"
+            >
+              <UploadIcon size={18} />
+            </button>
           </>
         )}
       />

frontend/src/styles/sidebar/sidebar.css

@@ -182,6 +182,24 @@
   outline-offset: 2px;
 }
 
+.sidebar__collapse-button {
+  color: color-mix(in oklch, var(--muted) 85%, transparent);
+  opacity: 0;
+  pointer-events: none;
+  transition: opacity 0.18s ease;
+}
+
+.sidebar:hover .sidebar__collapse-button,
+.sidebar__collapse-button:focus-visible {
+  opacity: 0.85;
+  pointer-events: auto;
+}
+
+.sidebar__collapse-button:hover:not([disabled]),
+.sidebar__collapse-button:focus-visible {
+  color: var(--muted);
+}
+
 .sidebar__title-chevron {
   transition: transform 0.2s ease;
 }
@@ -580,5 +598,3 @@
   background: var(--sidebar-active-bg);
   color: var(--fg);
 }
-
-