ci/cd: add svelte-check workflow for the frontend

.github/svelte-check-matcher.json

@@ -0,0 +1,21 @@
+{
+  "problemMatcher": [
+    {
+      "owner": "svelte-check",
+      "pattern": [
+        {
+          "regexp": "^([^\\s].*):(\\d+):(\\d+)$",
+          "file": 1,
+          "line": 2,
+          "column": 3
+        },
+        {
+          "regexp": "^\\s*(Error|Warning):\\s*(.*)\\s+\\((?:ts|js|svelte)\\)$",
+          "severity": 1,
+          "message": 2,
+          "loop": false
+        }
+      ]
+    }
+  ]
+}

.github/workflows/svelte-check.yml

@@ -0,0 +1,55 @@
+name: Svelte Check
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - "frontend/src/**"
+      - ".github/svelte-check-matcher.json"
+      - "frontend/package.json"
+      - "frontend/package-lock.json"
+      - "frontend/tsconfig.json"
+      - "frontend/svelte.config.js"
+  pull_request:
+    branches: [main]
+    paths:
+      - "frontend/src/**"
+      - ".github/svelte-check-matcher.json"
+      - "frontend/package.json"
+      - "frontend/package-lock.json"
+      - "frontend/tsconfig.json"
+      - "frontend/svelte.config.js"
+  workflow_dispatch:
+
+jobs:
+  type-check:
+    name: Run Svelte Check
+    # Don't run on dependabot branches
+    if: github.actor != 'dependabot[bot]'
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      checks: write
+      pull-requests: write
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: "lts/*"
+          cache: "npm"
+          cache-dependency-path: frontend/package-lock.json
+
+      - name: Install dependencies
+        working-directory: frontend
+        run: npm ci
+
+      - name: Add svelte-check problem matcher
+        run: echo "::add-matcher::.github/svelte-check-matcher.json"
+
+      - name: Run svelte-check
+        working-directory: frontend
+        run: npm run check