ci: add GitHub Actions workflow for releasing binaries

- Add .github/workflows/release.yml
- Build binaries for multiple platforms (linux/amd64, linux/arm64, darwin/amd64, darwin/arm64, windows/amd64)
- Embed frontend into binary
- Generate SHA256 checksums for each binary
- Automatically release on tag push

.github/workflows/release.yml

@@ -0,0 +1,92 @@
+name: Release Binaries
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+permissions:
+  contents: write
+
+jobs:
+  release:
+    name: Build and Release
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        include:
+          - goos: linux
+            goarch: amd64
+            suffix: linux-amd64
+          - goos: linux
+            goarch: arm64
+            suffix: linux-arm64
+          - goos: darwin
+            goarch: amd64
+            suffix: darwin-amd64
+          - goos: darwin
+            goarch: arm64
+            suffix: darwin-arm64
+          - goos: windows
+            goarch: amd64
+            suffix: windows-amd64
+            ext: .exe
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: '1.24'
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: 'pnpm'
+          cache-dependency-path: frontend/pnpm-lock.yaml
+
+      - name: Install pnpm
+        run: npm install -g pnpm
+
+      - name: Print build info
+        run: |
+          echo "Tag: ${{ github.ref_name }}"
+          echo "GoOS: ${{ matrix.goos }}"
+          echo "GoArch: ${{ matrix.goarch }}"
+
+      - name: Build frontend
+        working-directory: frontend
+        run: |
+          pnpm install --registry=https://registry.npmmirror.com
+          pnpm run build
+
+      - name: Copy frontend dist for embedding
+        run: |
+          mkdir -p internal/static/frontend
+          cp -r frontend/dist internal/static/frontend/
+
+      - name: Build binary
+        env:
+          GOOS: ${{ matrix.goos }}
+          GOARCH: ${{ matrix.goarch }}
+          CGO_ENABLED: 0
+        run: |
+          OUTPUT_NAME="ushare-${{ matrix.suffix }}${{ matrix.ext }}"
+          go build -ldflags '-s -w' -o "$OUTPUT_NAME" .
+          chmod +x "$OUTPUT_NAME"
+
+      - name: Generate checksums
+        run: |
+          OUTPUT_NAME="ushare-${{ matrix.suffix }}${{ matrix.ext }}"
+          sha256sum "$OUTPUT_NAME" > "$OUTPUT_NAME.sha256"
+
+      - name: Upload to release
+        uses: softprops/action-gh-release@v1
+        with:
+          files: |
+            ushare-${{ matrix.suffix }}${{ matrix.ext }}
+            ushare-${{ matrix.suffix }}${{ matrix.ext }}.sha256
+          draft: false
+          prerelease: false