Add mobile APK signing, build and release scripts

Add four new helper scripts for mobile APK workflows: setup-apk-signing.sh (decode keystores and export signing env vars), verify-apk-signature.sh (check and display APK certificate info), attach-apk-to-release.sh (rename and upload APK to a GitHub Release), and setup-mobile-github-secrets.sh (helper to generate/show required GitHub Secrets). Update product-release.yml to expose version/tag outputs and add a build-mobile-artifacts job that sets up Java/Flutter, installs deps, configures signing from repository secrets, builds APKs for worker/client apps, verifies signatures, uploads artifacts, and optionally attaches the APK to the GitHub Release. Secrets and envvar naming conventions are handled to support dev/staging/prod keystores; documentation references (docs/RELEASE/APK_SIGNING_SETUP.md) are noted in scripts.

.github/scripts/attach-apk-to-release.sh

@@ -0,0 +1,60 @@
+#!/bin/bash
+
+# =============================================================================
+# Attach APK to GitHub Release
+# =============================================================================
+# This script attaches a built APK to a GitHub Release with proper naming
+#
+# Usage:
+#   ./attach-apk-to-release.sh <tag_name> <app> <app_name> <version> <environment>
+#
+# Arguments:
+#   tag_name    - Git tag name (e.g., krow-withus-worker-mobile/dev-v0.1.0)
+#   app         - worker-mobile-app or client-mobile-app
+#   app_name    - staff or client (internal build folder name)
+#   version     - Version number (e.g., 0.1.0)
+#   environment - dev, stage, or prod
+#
+# Environment Variables:
+#   GH_TOKEN - GitHub token for gh CLI authentication
+# =============================================================================
+
+set -e
+
+TAG_NAME="$1"
+APP="$2"
+APP_NAME="$3"
+VERSION="$4"
+ENV="$5"
+
+if [ -z "$TAG_NAME" ] || [ -z "$APP" ] || [ -z "$APP_NAME" ] || [ -z "$VERSION" ] || [ -z "$ENV" ]; then
+    echo "❌ Error: Missing required arguments"
+    echo "Usage: $0 <tag_name> <app> <app_name> <version> <environment>"
+    exit 1
+fi
+
+# Find APK in build output
+APK_PATH="apps/mobile/apps/${APP_NAME}/build/app/outputs/flutter-apk/app-release.apk"
+
+if [ ! -f "$APK_PATH" ]; then
+    echo "❌ Error: APK not found at $APK_PATH"
+    echo "Searching for APK files..."
+    find apps/mobile/apps/${APP_NAME} -name "*.apk"
+    exit 1
+fi
+
+# Create proper APK name based on app type
+if [ "$APP" = "worker-mobile-app" ]; then
+    APK_NAME="krow-withus-worker-mobile-${ENV}-v${VERSION}.apk"
+else
+    APK_NAME="krow-withus-client-mobile-${ENV}-v${VERSION}.apk"
+fi
+
+# Copy APK with proper name
+cp "$APK_PATH" "/tmp/$APK_NAME"
+
+# Upload to GitHub Release
+echo "📤 Uploading $APK_NAME to release $TAG_NAME..."
+gh release upload "$TAG_NAME" "/tmp/$APK_NAME" --clobber
+
+echo "✅ APK attached to release: $APK_NAME"