Add visible focus styles to browse accordion and event items

Use inset outline on :focus-visible so the focus ring isn't clipped
by overflow: hidden on the era container.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: enricobattocchi

src/styles/Browse.module.css

@@ -88,6 +88,11 @@
   background: var(--color-bg-hover);
 }
 
+.eraHeader:focus-visible {
+  outline: 2px solid var(--color-primary);
+  outline-offset: -2px;
+}
+
 .eraInfo {
   flex: 1;
   display: flex;
@@ -148,6 +153,11 @@
   background: var(--color-bg-hover);
 }
 
+.eventItem:focus-visible {
+  outline: 2px solid var(--color-primary);
+  outline-offset: -2px;
+}
+
 .eventIcon {
   flex-shrink: 0;
   display: flex;