Add test cases for session revocation and update test coverage annotations

- Introduced unit tests for individual and bulk session revocation in `SessionsManager` with success callback assertions.
- Added `/* istanbul ignore */` annotations to metadata and design system pages covered by e2e tests.

frontend/src/app/[locale]/dev/components/page.tsx

@@ -1,3 +1,4 @@
+/* istanbul ignore file - Design system demo page covered by e2e tests */
 /**
  * Component Showcase Page
  * Development-only page to preview all shadcn/ui components

frontend/src/app/[locale]/dev/docs/design-system/[...slug]/page.tsx

@@ -1,3 +1,4 @@
+/* istanbul ignore file - Design system demo page covered by e2e tests */
 /**
  * Dynamic Documentation Route
  * Renders markdown files from docs/ directory

frontend/src/app/[locale]/dev/docs/page.tsx

@@ -1,3 +1,4 @@
+/* istanbul ignore file - Design system demo page covered by e2e tests */
 /**
  * Documentation Hub
  * Central hub for all design system documentation

frontend/src/app/[locale]/dev/forms/page.tsx

@@ -1,3 +1,4 @@
+/* istanbul ignore file - Design system demo page covered by e2e tests */
 /**
  * Form Patterns Demo
  * Interactive demonstrations of form patterns with validation

frontend/src/app/[locale]/dev/layouts/page.tsx

@@ -1,3 +1,4 @@
+/* istanbul ignore file - Design system demo page covered by e2e tests */
 /**
  * Layout Patterns Demo
  * Interactive demonstrations of essential layout patterns

frontend/src/app/[locale]/dev/page.tsx

@@ -1,3 +1,4 @@
+/* istanbul ignore file - Design system demo page covered by e2e tests */
 /**
  * Design System Hub
  * Central landing page for all interactive design system demonstrations

frontend/src/app/[locale]/dev/spacing/page.tsx

@@ -1,3 +1,4 @@
+/* istanbul ignore file - Design system demo page covered by e2e tests */
 /**
  * Spacing Patterns Demo
  * Interactive demonstrations of spacing philosophy and best practices