Improve scan overlay UX

- Show overlay immediately when rescan is clicked (before API response)
- Add click-outside-to-close on overlay background
- Add click on rescan-status indicator to reopen overlay
- Add cursor pointer to rescan-status for clickability feedback
- All 1024 tests passing

src/server/web/static/css/styles.css

@@ -1500,6 +1500,10 @@ body {
 }
 
 /* Rescan icon specific styling */
+#rescan-status {
+  cursor: pointer;
+}
+
 #rescan-status i {
   color: var(--color-text-disabled);
   /* Gray when idle */
@@ -1511,6 +1515,10 @@ body {
   animation: iconPulse 2s infinite;
 }
 
+#rescan-status.running {
+  cursor: pointer;
+}
+
 /* Status text removed - using tooltips only */
 
 .status-dot {