feat(ci): add Codecov integration with frontend Jest coverage and CODECOV_TOKEN

Agent-Logs-Url: https://github.com/christianlouis/InboxConverge/sessions/53f8deb9-5c3a-4940-a058-c8ee7e4104e0

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

frontend/package.json

@@ -6,7 +6,9 @@
     "dev": "next dev",
     "build": "next build",
     "start": "next start",
-    "lint": "eslint"
+    "lint": "eslint",
+    "test": "jest",
+    "test:ci": "jest --coverage --coverageReporters=lcov --passWithNoTests"
   },
   "dependencies": {
     "@tanstack/react-query": "^5.95.0",
@@ -19,11 +21,14 @@
   },
   "devDependencies": {
     "@tailwindcss/postcss": "^4",
+    "@types/jest": "^30.0.0",
     "@types/node": "^20",
     "@types/react": "^19",
     "@types/react-dom": "^19",
     "eslint": "^9",
     "eslint-config-next": "16.2.1",
+    "jest": "^30.3.0",
+    "jest-environment-jsdom": "^30.3.0",
     "tailwindcss": "^4",
     "typescript": "^5"
   }