build: remove expo.dev/EAS dependency, add local Android build pipeline

- Delete eas.json and strip extra.eas.projectId from app.json
- Add plugins/withAndroidReleaseSigning.js — Expo config plugin that injects
  release signingConfig into the generated build.gradle during expo prebuild
- Add build-apk.sh — self-contained build script (expo prebuild + Gradle)
  Reads keystore credentials from ~/.config/postiz-mobile/signing.env
  Outputs APK/AAB to dist/, wipes credentials from gradle.properties after build
- Add install-android-sdk.sh — one-time Android SDK cmdline-tools bootstrap
- Remove unused expo-task-manager dependency
- Update .gitignore: android/, ios/, static-build/ excluded (generated)

Build workflow:
  1. eas credentials --platform android  # export keystore once
  2. ./install-android-sdk.sh            # first time only
  3. ./build-apk.sh                      # → dist/postiz-mobile-YYYYMMDD-HHMM.apk

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

artifacts/postiz-mobile/build-apk.sh

@@ -0,0 +1,115 @@
+#!/usr/bin/env bash
+# build-apk.sh — Build a signed release APK locally without expo.dev / EAS.
+#
+# Prerequisites (first time only):
+#   1. Export EAS keystore:
+#        eas credentials --platform android
+#        → "Download existing keystore" → save to ~/.config/postiz-mobile/postiz-mobile.jks
+#   2. Fill in signing credentials:
+#        cp ~/.config/postiz-mobile/signing.env.example ~/.config/postiz-mobile/signing.env
+#        editor ~/.config/postiz-mobile/signing.env
+#   3. Install Android SDK (if not already):
+#        ./install-android-sdk.sh
+#
+# Usage:
+#   ./build-apk.sh              # APK goes to dist/
+#   ./build-apk.sh --aab        # AAB (Play Store) instead of APK
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+SIGNING_ENV="$HOME/.config/postiz-mobile/signing.env"
+DIST_DIR="$SCRIPT_DIR/dist"
+BUILD_TYPE="${1:-}"
+
+# ─── Colours ───────────────────────────────────────────────────────────────
+RED='\033[0;31m'; GREEN='\033[0;32m'; YELLOW='\033[1;33m'; NC='\033[0m'
+info()    { echo -e "${GREEN}[build]${NC} $*"; }
+warn()    { echo -e "${YELLOW}[warn]${NC}  $*"; }
+abort()   { echo -e "${RED}[error]${NC} $*" >&2; exit 1; }
+
+# ─── 1. Signing credentials ────────────────────────────────────────────────
+if [ ! -f "$SIGNING_ENV" ]; then
+  abort "Missing signing.env.\n\n  cp ~/.config/postiz-mobile/signing.env.example ~/.config/postiz-mobile/signing.env\n  # then fill in your keystore path and passwords"
+fi
+# shellcheck source=/dev/null
+source "$SIGNING_ENV"
+
+[ -z "${KEYSTORE_PATH:-}" ]           && abort "KEYSTORE_PATH not set in signing.env"
+[ -z "${KEYSTORE_ALIAS:-}" ]          && abort "KEYSTORE_ALIAS not set in signing.env"
+[ -z "${KEYSTORE_STORE_PASSWORD:-}" ] && abort "KEYSTORE_STORE_PASSWORD not set in signing.env"
+[ -z "${KEYSTORE_KEY_PASSWORD:-}" ]   && abort "KEYSTORE_KEY_PASSWORD not set in signing.env"
+
+KEYSTORE_PATH_EXPANDED="${KEYSTORE_PATH/#\$HOME/$HOME}"
+KEYSTORE_PATH_EXPANDED="${KEYSTORE_PATH_EXPANDED/#~/$HOME}"
+
+[ ! -f "$KEYSTORE_PATH_EXPANDED" ] && abort "Keystore not found: $KEYSTORE_PATH_EXPANDED\n\nExport it from EAS:\n  eas credentials --platform android\n  → Download existing keystore → save to $KEYSTORE_PATH_EXPANDED"
+
+# ─── 2. Android SDK ────────────────────────────────────────────────────────
+if [ -z "${ANDROID_HOME:-}" ]; then
+  # Try common locations
+  for candidate in "$HOME/android-sdk" "$HOME/Android/Sdk" "/opt/android-sdk"; do
+    if [ -d "$candidate/platform-tools" ]; then
+      export ANDROID_HOME="$candidate"
+      break
+    fi
+  done
+fi
+
+if [ -z "${ANDROID_HOME:-}" ]; then
+  abort "Android SDK not found.\n\nRun: ./install-android-sdk.sh\nOr set ANDROID_HOME manually in your shell."
+fi
+
+export PATH="$PATH:$ANDROID_HOME/platform-tools:$ANDROID_HOME/cmdline-tools/latest/bin"
+info "Android SDK: $ANDROID_HOME"
+
+# ─── 3. expo prebuild ──────────────────────────────────────────────────────
+info "Running expo prebuild (Android)…"
+cd "$SCRIPT_DIR"
+pnpm exec expo prebuild --platform android --clean --no-install
+
+# ─── 4. Inject signing into gradle.properties ──────────────────────────────
+info "Injecting signing credentials into gradle.properties…"
+GRADLE_PROPS="$SCRIPT_DIR/android/gradle.properties"
+
+# Remove any previous signing block written by this script
+sed -i '/^# --- postiz-mobile release signing/,/^# --- end signing/d' "$GRADLE_PROPS" 2>/dev/null || true
+
+cat >> "$GRADLE_PROPS" << EOF
+
+# --- postiz-mobile release signing (injected by build-apk.sh)
+MYAPP_UPLOAD_STORE_FILE=$KEYSTORE_PATH_EXPANDED
+MYAPP_UPLOAD_STORE_PASSWORD=$KEYSTORE_STORE_PASSWORD
+MYAPP_UPLOAD_KEY_ALIAS=$KEYSTORE_ALIAS
+MYAPP_UPLOAD_KEY_PASSWORD=$KEYSTORE_KEY_PASSWORD
+# --- end signing
+EOF
+
+# ─── 5. Gradle build ───────────────────────────────────────────────────────
+cd "$SCRIPT_DIR/android"
+
+if [ "$BUILD_TYPE" = "--aab" ]; then
+  info "Building AAB (release)…"
+  ./gradlew bundleRelease
+  ARTIFACT="app/build/outputs/bundle/release/app-release.aab"
+  EXT="aab"
+else
+  info "Building APK (release)…"
+  ./gradlew assembleRelease
+  ARTIFACT="app/build/outputs/apk/release/app-release.apk"
+  EXT="apk"
+fi
+
+# ─── 6. Copy to dist/ ──────────────────────────────────────────────────────
+mkdir -p "$DIST_DIR"
+TIMESTAMP="$(date +%Y%m%d-%H%M)"
+OUTPUT="$DIST_DIR/postiz-mobile-$TIMESTAMP.$EXT"
+cp "$ARTIFACT" "$OUTPUT"
+
+echo ""
+info "Build complete!"
+echo -e "  ${GREEN}→ $OUTPUT${NC}"
+echo ""
+
+# Wipe signing credentials from gradle.properties for safety
+sed -i '/^# --- postiz-mobile release signing/,/^# --- end signing/d' "$GRADLE_PROPS"