ci(release): add Linux x86_64 and Android APK release workflow

Tag-triggered (v*) workflow builds a Linux tarball (binary + assets) and
a multi-arch Android APK signed with a release keystore stored in GitHub
secrets. A final job creates the GitHub Release with both files attached
so Obtainium can track and auto-download the APK.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.github/workflows/release.yml

@@ -0,0 +1,162 @@
+name: Release
+
+# Triggered by pushing a version tag, e.g. `git tag v0.22.0 && git push origin v0.22.0`.
+# Builds a Linux x86_64 tarball and a signed Android APK, then publishes
+# both as assets on a GitHub Release. Obtainium can track this repo's
+# releases and download the APK automatically.
+#
+# Required repository secrets (Settings → Secrets and variables → Actions):
+#   ANDROID_KEYSTORE_BASE64      base64-encoded .jks file (see README for gen command)
+#   ANDROID_KEYSTORE_PASSWORD    password used with -storepass when creating the keystore
+#   ANDROID_KEY_ALIAS            alias used with -alias when creating the keystore
+#   ANDROID_KEY_PASSWORD         password used with -keypass when creating the keystore
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+permissions:
+  contents: write   # gh release create needs write access
+
+env:
+  CARGO_TERM_COLOR: always
+  RUSTFLAGS: "-D warnings"
+
+# ---------------------------------------------------------------------------
+# Job 1: Linux x86_64 binary + assets tarball
+# ---------------------------------------------------------------------------
+jobs:
+  build-linux:
+    name: Build · Linux x86_64
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust stable
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Install system deps
+        run: |
+          sudo apt-get update -qq
+          sudo apt-get install -y --no-install-recommends \
+            libasound2-dev libudev-dev libwayland-dev libxkbcommon-dev
+
+      - name: Cache cargo registry + build artifacts
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: linux-release-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: linux-release-
+
+      - name: Build release binary
+        run: cargo build --release -p solitaire_app
+
+      - name: Package tarball
+        run: |
+          mkdir solitaire-quest
+          cp target/release/solitaire_app solitaire-quest/
+          cp -r assets solitaire-quest/
+          tar -czf solitaire-quest-linux-x86_64.tar.gz solitaire-quest
+
+      - uses: actions/upload-artifact@v4
+        with:
+          name: linux
+          path: solitaire-quest-linux-x86_64.tar.gz
+
+# ---------------------------------------------------------------------------
+# Job 2: Android APK (multi-arch) — debug-built then release-signed
+# ---------------------------------------------------------------------------
+  build-android:
+    name: Build · Android APK
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust stable + Android targets
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: aarch64-linux-android,armv7-linux-androideabi,x86_64-linux-android
+
+      - name: Expose NDK root to cargo-apk
+        # ANDROID_NDK_LATEST_HOME is set by the GitHub-hosted runner.
+        # cargo-apk reads ANDROID_NDK_ROOT; write it to GITHUB_ENV so
+        # all subsequent steps in this job inherit it.
+        run: echo "ANDROID_NDK_ROOT=$ANDROID_NDK_LATEST_HOME" >> $GITHUB_ENV
+
+      - name: Cache cargo registry + cargo-apk binary + build artifacts
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            ~/.cargo/bin
+            target
+          key: android-release-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: android-release-
+
+      - name: Install cargo-apk
+        # --locked: use the dependency versions cargo-apk was tested with.
+        # cargo install is a no-op when the cached binary is already current.
+        run: cargo install --locked cargo-apk
+
+      - name: Build APK (release profile)
+        run: cargo apk build -p solitaire_app --release
+
+      - name: Sign APK with release keystore
+        run: |
+          # Restore the keystore from the base64-encoded secret.
+          echo "${{ secrets.ANDROID_KEYSTORE_BASE64 }}" | base64 -d > release.keystore
+
+          # Locate apksigner from whichever build-tools version the runner provides.
+          BUILD_TOOLS=$(ls "$ANDROID_HOME/build-tools" | sort -V | tail -1)
+          APKSIGNER="$ANDROID_HOME/build-tools/$BUILD_TOOLS/apksigner"
+
+          "$APKSIGNER" sign \
+            --ks release.keystore \
+            --ks-key-alias "${{ secrets.ANDROID_KEY_ALIAS }}" \
+            --ks-pass "pass:${{ secrets.ANDROID_KEYSTORE_PASSWORD }}" \
+            --key-pass "pass:${{ secrets.ANDROID_KEY_PASSWORD }}" \
+            --out "solitaire-quest-${{ github.ref_name }}.apk" \
+            target/release/apk/solitaire-quest.apk
+
+          # Remove keystore immediately — never leave it as a build artifact.
+          rm release.keystore
+
+      - uses: actions/upload-artifact@v4
+        with:
+          name: android
+          path: solitaire-quest-${{ github.ref_name }}.apk
+
+# ---------------------------------------------------------------------------
+# Job 3: Create the GitHub Release once both builds succeed
+# ---------------------------------------------------------------------------
+  release:
+    name: Publish GitHub Release
+    runs-on: ubuntu-latest
+    needs: [build-linux, build-android]
+
+    steps:
+      - uses: actions/download-artifact@v4
+        with:
+          name: linux
+
+      - uses: actions/download-artifact@v4
+        with:
+          name: android
+
+      - name: Create GitHub Release
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          gh release create "${{ github.ref_name }}" \
+            --repo "${{ github.repository }}" \
+            --title "Solitaire Quest ${{ github.ref_name }}" \
+            --generate-notes \
+            "solitaire-quest-linux-x86_64.tar.gz" \
+            "solitaire-quest-${{ github.ref_name }}.apk"