a11y(dashboard): retire superseded new-tab announcement lane

.jules/palette.md

@@ -81,3 +81,7 @@
 ## 2026-08-12 - Skip to Content Accessibility
 **Learning:** Screen reader and keyboard-only users experience significant friction when forced to navigate through repetitive header controls on every page load.
 **Action:** Keep a visible-on-focus skip link as the first interactive element, target a programmatically focusable main container, and give the focused link a high-contrast outline.
+
+## 2026-09-08 - Context switch warning for external links
+**Learning:** Links opening in a new tab (`target="_blank"`) cause an unexpected context switch for screen reader users, confusing navigation.
+**Action:** When using `target="_blank"`, always add `aria-label="[Link name] (opens in a new tab)"` or a visually hidden text element to explicitly warn screen reader users of the context switch.

scanner/dashboard/index.html

@@ -281,7 +281,7 @@ <h1>Dashboard</h1>
 function openDetail(f){
   lastFocus = document.activeElement;
   const s = String(f.severity||'INFO').toUpperCase();
-  const refs = (f.references||[]).map(r=>`<a href="${esc(safeUrl(r))}" target="_blank" rel="noopener">${esc(r)}</a>`).join('<br>');
+  const refs = (f.references||[]).map(r=>`<a href="${esc(safeUrl(r))}" target="_blank" rel="noopener" aria-label="${esc(r)} (opens in a new tab)">${esc(r)}</a>`).join('<br>');
   const owasp = (f.owasp||[]).join(', ');
   const cwe = (f.cwe||[]).join(', ');
   const d = document.getElementById('detail');