ci(artifacts): build and package demo app artifacts cross-target

- cross-compile examples/demo_app with demo-monitor when
  upload-artifacts is true and a target is provided
- package demo binary as medicallib_demo_app-<version>-<triple> archive
  with bin/<demo_app> included
- add strict bash flags, ensure dist dir exists, and fail early if the
  demo binary is missing
- use platform linkers via env for linux/windows GNU targets
- keep existing library package; now upload both artifacts

.gitea/workflows/ci-reusable.yml

@@ -79,10 +79,19 @@ jobs:
           CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_LINKER: x86_64-linux-gnu-g++
           CARGO_TARGET_X86_64_PC_WINDOWS_GNU_LINKER: x86_64-w64-mingw32-gcc
 
+      - name: Build demo app (Cross-Compile)
+        if: inputs.upload-artifacts && inputs.target != ''
+        run: cargo build --release --example demo_app --features demo-monitor --target=${{ inputs.target }}
+        env:
+          CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_LINKER: x86_64-linux-gnu-g++
+          CARGO_TARGET_X86_64_PC_WINDOWS_GNU_LINKER: x86_64-w64-mingw32-gcc
+
       - name: Extract version and create package
         if: inputs.upload-artifacts
         shell: bash
         run: |
+          set -euo pipefail
+
           VERSION=$(sed -n 's/^version\s*=\s*"\([^"]\+\)"/\1/p' Cargo.toml | head -n1)
           TARGET_ARCH="x86_64"
           TARGET_TRIPLE="${{ inputs.target }}"
@@ -90,17 +99,29 @@ jobs:
           # Determine package name and library extension based on target
           if [[ "$TARGET_TRIPLE" == "x86_64-unknown-linux-gnu" ]]; then
             PKG_BASENAME="medicallib_rust-v${VERSION}-${TARGET_ARCH}-unknown-linux-gnu"
+            DEMO_PKG_BASENAME="medicallib_demo_app-v${VERSION}-${TARGET_ARCH}-unknown-linux-gnu"
             LIB_NAME="libmedicallib_rust.so"
+            DEMO_BINARY_NAME="demo_app"
             ARCHIVE_TYPE="tar.gz"
           elif [[ "$TARGET_TRIPLE" == "x86_64-pc-windows-gnu" ]]; then
             PKG_BASENAME="medicallib_rust-v${VERSION}-${TARGET_ARCH}-pc-windows-gnu"
+            DEMO_PKG_BASENAME="medicallib_demo_app-v${VERSION}-${TARGET_ARCH}-pc-windows-gnu"
             LIB_NAME="medicallib_rust.dll"
+            DEMO_BINARY_NAME="demo_app.exe"
             ARCHIVE_TYPE="zip"
           else
             echo "::error::Unsupported target for packaging: $TARGET_TRIPLE"
             exit 1
           fi
 
+          DEMO_BINARY_SOURCE="target/${TARGET_TRIPLE}/release/examples/${DEMO_BINARY_NAME}"
+
+          if [[ ! -f "$DEMO_BINARY_SOURCE" ]]; then
+            echo "::error::Demo binary not found at $DEMO_BINARY_SOURCE"
+            exit 1
+          fi
+
+          mkdir -p dist
           PKG_DIR="dist/${PKG_BASENAME}"
           echo "Creating package ${PKG_BASENAME}..."
           mkdir -p "${PKG_DIR}/include" "${PKG_DIR}/lib"
@@ -109,11 +130,18 @@ jobs:
           cp ffi/medicallib.h "${PKG_DIR}/include/"
           cp "target/${TARGET_TRIPLE}/release/${LIB_NAME}" "${PKG_DIR}/lib/"
 
+          DEMO_DIR="dist/${DEMO_PKG_BASENAME}"
+          echo "Creating demo package ${DEMO_PKG_BASENAME}..."
+          mkdir -p "${DEMO_DIR}/bin"
+          cp "$DEMO_BINARY_SOURCE" "${DEMO_DIR}/bin/${DEMO_BINARY_NAME}"
+
           # Create the appropriate archive
           if [[ "$ARCHIVE_TYPE" == "tar.gz" ]]; then
             tar -C dist -czf "dist/${PKG_BASENAME}.tar.gz" "${PKG_BASENAME}"
+            tar -C dist -czf "dist/${DEMO_PKG_BASENAME}.tar.gz" "${DEMO_PKG_BASENAME}"
           elif [[ "$ARCHIVE_TYPE" == "zip" ]]; then
             (cd dist && zip -r9 "${PKG_BASENAME}.zip" "${PKG_BASENAME}")
+            (cd dist && zip -r9 "${DEMO_PKG_BASENAME}.zip" "${DEMO_PKG_BASENAME}")
           fi
 
       - name: Upload Artifact
@@ -123,4 +151,4 @@ jobs:
           # Create a unique name based on the target OS
           name: medicallib-rust-${{ contains(inputs.target, 'windows') && 'Windows' || 'Linux' }}-x86_64-${{ github.run_number }}
           path: dist/
-          if-no-files-found: error
+          if-no-files-found: error