Apply and Upgrade Eslint (#288)

* Upgrade ESLINT and fix issues

* feat: add frontend linting job to GitHub Actions workflow

* Move UI linting to separate file

* More linting fixes

* Remove pull_request trigger from UI linting workflow

* Update UI linting workflow

* Rename frontend-lint workflow to ui-lint for clarity

.github/workflows/ui-lint.yml

@@ -0,0 +1,34 @@
+---
+name: ui-lint
+on:
+  push:
+    paths:
+      - "ui/**"
+      - "package.json"
+      - "package-lock.json"
+      - ".github/workflows/ui-lint.yml"
+
+permissions:
+  contents: read
+
+jobs:
+  ui-lint:
+    name: UI Lint
+    runs-on: buildjet-4vcpu-ubuntu-2204
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+      - name: Set up Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: v21.1.0
+          cache: "npm"
+          cache-dependency-path: "ui/package-lock.json"
+      - name: Install dependencies
+        run: |
+          cd ui
+          npm ci
+      - name: Lint UI
+        run: |
+          cd ui
+          npm run lint