fix: address Copilot review comments on accessibility PR #616

- Add aria-pressed attribute to high-contrast toggle button in App.vue
  so assistive technology can announce the button's on/off state
- Fix lint formatting in a11y.spec.ts error page test declaration

Notes on pre-existing fixes verified in this pass:
- CountdownTimer unit tests for SR announcements already present
- ErrorToasts compact spacing test already present
- SCALE_COMPONENT_EXCLUDES replaced by isScaleShadowDomNode() filter
- router/index.ts already cancels focusTimerId on every navigation
- localStorage guarded with try/catch in both getInitialHighContrast/toggleHighContrast
- BreakglassSessionCard/BreakglassCard cluster duplication already fixed
- NotFoundView CTA already uses CSS variables

Author: MaxRink

frontend/src/App.vue

@@ -414,6 +414,7 @@ watch(
               type="button"
               :class="['hc-toggle-button', { 'hc-active': highContrast }]"
               :aria-label="highContrast ? 'Disable high contrast mode' : 'Enable high contrast mode'"
+              :aria-pressed="highContrast"
               @click="toggleHighContrast"
             >
               <scale-icon-action-eye :decorative="true"></scale-icon-action-eye>

frontend/tests/e2e/a11y.spec.ts

@@ -344,7 +344,9 @@ test.describe("Accessibility (axe-core WCAG 2.1 AA + AAA)", () => {
 
       // ── Error pages ──────────────────────────────────────────────
       for (const errorPage of ERROR_PAGES_TO_AUDIT) {
-        test(`${errorPage.name} (${errorPage.path}) has no critical/serious a11y violations [${mode.name}]`, async ({ page }) => {
+        test(`${errorPage.name} (${errorPage.path}) has no critical/serious a11y violations [${mode.name}]`, async ({
+          page,
+        }) => {
           await mode.setup(page);
 
           await performMockLogin(page);