chore: add ESLint plugin and rules to remove unused imports

- Installed eslint-plugin-unused-imports
- Updated .eslintrc.json to include rules for detecting unused imports

.eslintrc.json

@@ -1,4 +1,7 @@
 {
   "extends": "next/core-web-vitals",
-  "plugins": ["prettier"]
+  "plugins": ["prettier", "unused-imports"],
+  "rules": {
+    "unused-imports/no-unused-imports": "warn"
+  }
 }