feat(graph): add Federation Graph page and enhance coverage

Adds a new Federation Graph page to display subgraphs and their 
schemas. Implements loading state and error handling. Enhances 
coverage reporting by including 'lcov' format for better insights 
into test coverage metrics.

test/setup.ts

@@ -2,16 +2,36 @@ import { config } from '@vue/test-utils'
 import { vi } from 'vitest'
 import * as Vue from 'vue'
 
-// Mock localStorage
-const localStorageMock = {
-  getItem: vi.fn(),
-  setItem: vi.fn(),
-  removeItem: vi.fn(),
-  clear: vi.fn(),
-  key: vi.fn(),
-  length: 0,
+// Mock localStorage with actual implementation
+class LocalStorageMock {
+  private store: Map<string, string> = new Map()
+
+  getItem(key: string): string | null {
+    return this.store.get(key) ?? null
+  }
+
+  setItem(key: string, value: string): void {
+    this.store.set(key, value)
+  }
+
+  removeItem(key: string): void {
+    this.store.delete(key)
+  }
+
+  clear(): void {
+    this.store.clear()
+  }
+
+  key(index: number): string | null {
+    return Array.from(this.store.keys())[index] ?? null
+  }
+
+  get length(): number {
+    return this.store.size
+  }
 }
-global.localStorage = localStorageMock as unknown as Storage
+
+global.localStorage = new LocalStorageMock() as unknown as Storage
 
 // Make Vue composables globally available
 global.ref = Vue.ref
@@ -87,7 +107,31 @@ config.global.stubs = {
   VIcon: {
     name: 'v-icon',
     template: '<i class="v-icon" :class="icon" @click="$emit(\'click\')"></i>',
-    props: ['icon', 'large'],
+    props: ['icon', 'large', 'start', 'end', 'size'],
     emits: ['click'],
   },
+  VMenu: {
+    name: 'v-menu',
+    template: '<div class="v-menu"><slot name="activator" :props="{}" /><slot /></div>',
+    props: ['modelValue', 'closeOnContentClick'],
+  },
+  VList: {
+    name: 'v-list',
+    template: '<div class="v-list"><slot /></div>',
+  },
+  VListItem: {
+    name: 'v-list-item',
+    template: '<div class="v-list-item" :data-active="active" @click="$emit(\'click\')"><slot /><slot name="append" /></div>',
+    props: ['active', 'value'],
+    emits: ['click'],
+  },
+  VListItemTitle: {
+    name: 'v-list-item-title',
+    template: '<div class="v-list-item-title"><slot /></div>',
+  },
+  VChip: {
+    name: 'v-chip',
+    template: '<div class="v-chip" :class="variant"><slot /></div>',
+    props: ['size', 'variant', 'prependIcon'],
+  },
 }