feat: GitHub Release workflow + Homebrew tap + install badges

- .github/workflows/release.yml: builds prebuilt binaries for
  macOS (arm64, x86_64) and Linux (x86_64, aarch64) on tag push.
  Creates GitHub Release with tarballs + SHA256SUMS.
  Auto-updates Homebrew formula via bump-homebrew-formula-action.

- README: added GitHub download count + npm install count badges.
  Install section now lists: Homebrew, prebuilt binaries, cargo
  install --git, Docker, Docker Compose.

- Homebrew tap created at github.com/0xMassi/homebrew-webclaw
  with Formula/webclaw.rb (installs webclaw + webclaw-mcp binaries).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/release.yml

@@ -0,0 +1,109 @@
+name: Release
+
+on:
+  push:
+    tags: ["v*"]
+
+permissions:
+  contents: write
+
+env:
+  CARGO_TERM_COLOR: always
+  RUSTFLAGS: "--cfg reqwest_unstable"
+
+jobs:
+  build:
+    name: Build ${{ matrix.target }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - target: x86_64-apple-darwin
+            os: macos-13
+          - target: aarch64-apple-darwin
+            os: macos-14
+          - target: x86_64-unknown-linux-gnu
+            os: ubuntu-latest
+          - target: aarch64-unknown-linux-gnu
+            os: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: ${{ matrix.target }}
+
+      - uses: Swatinem/rust-cache@v2
+        with:
+          key: ${{ matrix.target }}
+
+      # Cross-compilation support for aarch64-linux
+      - name: Install cross-compilation tools
+        if: matrix.target == 'aarch64-unknown-linux-gnu'
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y gcc-aarch64-linux-gnu
+          echo "CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER=aarch64-linux-gnu-gcc" >> $GITHUB_ENV
+
+      - name: Build
+        run: cargo build --release --target ${{ matrix.target }}
+
+      - name: Package
+        shell: bash
+        run: |
+          tag="${GITHUB_REF#refs/tags/}"
+          staging="webclaw-${tag}-${{ matrix.target }}"
+          mkdir "$staging"
+          cp target/${{ matrix.target }}/release/webclaw "$staging/" 2>/dev/null || true
+          cp target/${{ matrix.target }}/release/webclaw-mcp "$staging/" 2>/dev/null || true
+          cp README.md LICENSE "$staging/"
+          tar czf "$staging.tar.gz" "$staging"
+          echo "ASSET=$staging.tar.gz" >> $GITHUB_ENV
+
+      - name: Upload artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: ${{ matrix.target }}
+          path: ${{ env.ASSET }}
+
+  release:
+    name: Release
+    needs: build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/download-artifact@v4
+        with:
+          path: artifacts
+
+      - name: Compute checksums
+        run: |
+          cd artifacts
+          find . -name '*.tar.gz' -exec mv {} . \;
+          sha256sum *.tar.gz > SHA256SUMS
+          cat SHA256SUMS
+
+      - name: Create GitHub Release
+        uses: softprops/action-gh-release@v2
+        with:
+          generate_release_notes: true
+          files: |
+            artifacts/*.tar.gz
+            artifacts/SHA256SUMS
+
+  homebrew:
+    name: Update Homebrew
+    needs: release
+    runs-on: ubuntu-latest
+    steps:
+      - name: Update Homebrew formula
+        uses: mislav/bump-homebrew-formula-action@v3
+        with:
+          formula-name: webclaw
+          homebrew-tap: 0xMassi/homebrew-webclaw
+          download-url: https://github.com/0xMassi/webclaw/releases/download/${{ github.ref_name }}/webclaw-${{ github.ref_name }}-aarch64-apple-darwin.tar.gz
+        env:
+          COMMITTER_TOKEN: ${{ secrets.HOMEBREW_TAP_TOKEN }}