feat: android webview app + APK build script + CI artifact

Android app (WebView wrapper):
- Wraps the public household sharing URL in a native Android app
- Swipe-to-refresh, error handling, back navigation, settings dialog
- User enters their household's public URL on first launch
- Material Design with toolbar, progress indicator

Build tooling:
- build-apk.sh: one-command APK build (auto-installs Java, SDK, Gradle)
- .gitignore updated for Android build artifacts

CI (.gitea/workflows/ci.yml):
- New 'build-android' job (needs test-and-package)
- Installs Android SDK + Java 17, builds debug APK
- Uploads APK as 'meal-tracker-apk' artifact

build-apk.sh

@@ -0,0 +1,171 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# ── build-apk.sh ──────────────────────────────────────────────────────────────
+# Builds the Meal Tracker Android APK from the android/ directory.
+#
+# Usage:
+#   ./build-apk.sh              # Build debug APK (default)
+#   ./build-apk.sh release      # Build release APK (unsigned)
+#
+# Prerequisites (auto-installed if missing):
+#   - Java 17+ (OpenJDK)
+#   - Android SDK command-line tools
+#   - Gradle (via wrapper)
+# ──────────────────────────────────────────────────────────────────────────────
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+ANDROID_DIR="$SCRIPT_DIR/android"
+OUTPUT_DIR="$ANDROID_DIR/app/build/outputs/apk"
+SDK_ROOT="${ANDROID_SDK_ROOT:-$HOME/android-sdk}"
+CMDLINE_URL="https://dl.google.com/android/repository/commandlinetools-linux-11076708_latest.zip"
+BUILD_TOOLS_VER="34.0.0"
+PLATFORM_VER="34"
+GRADLE_VER="8.7"
+GRADLE_URL="https://services.gradle.org/distributions/gradle-${GRADLE_VER}-bin.zip"
+
+BUILD_TYPE="${1:-debug}"
+
+# ── Colors ──
+RED='\033[0;31m'; GREEN='\033[0;32m'; YELLOW='\033[1;33m'; NC='\033[0m'
+info()  { echo -e "${GREEN}[INFO]${NC}  $*"; }
+warn()  { echo -e "${YELLOW}[WARN]${NC}  $*"; }
+err()   { echo -e "${RED}[ERR]${NC}   $*"; }
+
+# ── Detect package manager ──
+if command -v apt-get &>/dev/null; then
+    PM="apt"
+elif command -v yum &>/dev/null; then
+    PM="yum"
+elif command -v dnf &>/dev/null; then
+    PM="dnf"
+else
+    PM=""
+fi
+
+# ── Install Java if needed ──
+install_java() {
+    info "Installing Java 17..."
+    case "$PM" in
+        apt)
+            apt-get update -qq && apt-get install -y -qq openjdk-21-jdk-headless ;;
+        yum)
+            yum install -y java-17-openjdk-headless ;;
+        dnf)
+            dnf install -y java-17-openjdk-headless ;;
+        *)
+            err "Cannot install Java automatically. Please install Java 17+ manually."
+            exit 1
+            ;;
+    esac
+}
+
+if ! command -v java &>/dev/null; then
+    if [ "$PM" != "" ]; then
+        install_java
+    else
+        err "Java is required but not found. Install Java 17+ (OpenJDK)."
+        exit 1
+    fi
+fi
+
+JAVA_VER=$(java -version 2>&1 | head -1 | grep -oP '\d+' | head -1 || echo "0")
+if [ "$JAVA_VER" -lt 17 ] 2>/dev/null; then
+    warn "Java $JAVA_VER detected. Java 17+ is recommended."
+fi
+info "Java: $(java -version 2>&1 | head -1)"
+
+# ── Install Android SDK if needed ──
+install_sdk() {
+    info "Installing Android SDK command-line tools to $SDK_ROOT..."
+    mkdir -p "$SDK_ROOT"
+    tmp_zip="/tmp/cmdline-tools.zip"
+    tmp_dir="/tmp/cmdline-tools-tmp"
+
+    if command -v wget &>/dev/null; then
+        wget -q --show-progress "$CMDLINE_URL" -O "$tmp_zip"
+    elif command -v curl &>/dev/null; then
+        curl -L --progress-bar "$CMDLINE_URL" -o "$tmp_zip"
+    else
+        err "Need wget or curl to download Android SDK."
+        exit 1
+    fi
+
+    rm -rf "$tmp_dir"
+    mkdir -p "$tmp_dir"
+    unzip -qo "$tmp_zip" -d "$tmp_dir"
+    mkdir -p "$SDK_ROOT/cmdline-tools"
+    rm -rf "$SDK_ROOT/cmdline-tools/latest"
+    mv "$tmp_dir/cmdline-tools" "$SDK_ROOT/cmdline-tools/latest"
+    rm -f "$tmp_zip"
+    rm -rf "$tmp_dir"
+    info "Android SDK command-line tools installed."
+}
+
+if [ ! -f "$SDK_ROOT/cmdline-tools/latest/bin/sdkmanager" ]; then
+    install_sdk
+fi
+
+export ANDROID_SDK_ROOT="$SDK_ROOT"
+
+# Accept SDK licenses
+yes | "$SDK_ROOT/cmdline-tools/latest/bin/sdkmanager" --licenses > /dev/null 2>&1 || true
+
+# ── Install required SDK packages ──
+info "Checking Android SDK packages..."
+"$SDK_ROOT/cmdline-tools/latest/bin/sdkmanager" \
+    "platform-tools" \
+    "build-tools;${BUILD_TOOLS_VER}" \
+    "platforms;android-${PLATFORM_VER}" \
+    > /dev/null 2>&1 || true
+
+# Create local.properties
+cat > "$ANDROID_DIR/local.properties" <<EOF
+sdk.dir=$SDK_ROOT
+EOF
+
+# ── Download Gradle if needed ──
+GRADLE_DIR="$ANDROID_DIR/.gradle-home"
+GRADLE_BIN="$GRADLE_DIR/gradle-${GRADLE_VER}/bin/gradle"
+if [ ! -f "$GRADLE_BIN" ]; then
+    info "Downloading Gradle ${GRADLE_VER}..."
+    gradle_zip="/tmp/gradle-${GRADLE_VER}.zip"
+    if command -v wget &>/dev/null; then
+        wget -q --show-progress "$GRADLE_URL" -O "$gradle_zip"
+    else
+        curl -L --progress-bar "$GRADLE_URL" -o "$gradle_zip"
+    fi
+    rm -rf "$GRADLE_DIR"
+    mkdir -p "$GRADLE_DIR"
+    unzip -qo "$gradle_zip" -d "$GRADLE_DIR"
+    rm -f "$gradle_zip"
+    info "Gradle ${GRADLE_VER} ready."
+fi
+
+# Generate wrapper in the android dir so gradlew works
+if [ ! -f "$ANDROID_DIR/gradlew" ]; then
+    info "Generating Gradle wrapper..."
+    cd "$ANDROID_DIR"
+    "$GRADLE_BIN" wrapper --gradle-version "$GRADLE_VER" --no-daemon 2>&1 | tail -3
+    cd "$SCRIPT_DIR"
+fi
+
+# ── Build ──
+info "Building $BUILD_TYPE APK..."
+cd "$ANDROID_DIR"
+./gradlew "assemble${BUILD_TYPE^}" --no-daemon --warning-mode=all
+
+# ── Report ──
+APK_FILE=$(find "$OUTPUT_DIR" -name "*.apk" -type f | head -1)
+if [ -f "$APK_FILE" ]; then
+    APK_SIZE=$(du -h "$APK_FILE" | cut -f1)
+    echo ""
+    echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+    echo -e "  ${GREEN}✓ BUILD SUCCESSFUL${NC}"
+    echo "  APK: $APK_FILE"
+    echo "  Size: $APK_SIZE"
+    echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+else
+    err "APK not found in $OUTPUT_DIR"
+    exit 1
+fi