chore: use Task, split workflows

.github/workflows/build.yaml

@@ -0,0 +1,33 @@
+name: Build
+
+on:
+  push:
+    branches:
+      - "master"
+    tags:
+      - "v*"
+  pull_request:
+
+jobs:
+  build:
+    name: Frontend and Backend
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+        with:
+          fetch-depth: 0
+      - uses: actions/setup-go@v6
+        with:
+          go-version: '1.25'
+      - uses: pnpm/action-setup@v4
+        with:
+          package_json_file: "frontend/package.json"
+      - uses: actions/setup-node@v6
+        with:
+          node-version: "24.x"
+          cache: "pnpm"
+          cache-dependency-path: "frontend/pnpm-lock.yaml"
+      - name: Install Task
+        uses: go-task/setup-task@v1
+      - run: task build
+