build: upgrade to Flutter 3.47.4 (AGP 9.1 / Gradle 9.3, iOS 15 + UIScene), refresh deps and CI

Flutter 3.24.5 -> 3.47.4 with the matching toolchain changes:

- pubspec: Dart ^3.11, Firebase core 4 / auth 6 / firestore 6 / storage 13,
  drop unused image_cropper, logging, change_app_package_name,
  pdf_widget_wrapper; pin path_provider_android <2.3 (needs NDK/CMake, not
  feasible on the ARM64 Gitea runner)
- Dart: CardTheme -> CardThemeData, replace deprecated withOpacity,
  Matrix4.scale, DropdownButtonFormField.value
- iOS: deployment target 15.0, UIScene lifecycle (AppDelegate/Info.plist),
  untrack stale Podfile.lock, add LaunchImage asset set
- Android: Gradle 9.3.1, AGP 9.1.0, Kotlin 2.4.0, google-services 4.5.0,
  layout.buildDirectory instead of removed Project.buildDir, remove manifest
  package attribute and duplicate MainActivity, kotlin.incremental=false
- CI: pin FLUTTER_VERSION in both workflows; iOS on macos-26 with SwiftPM
  disabled (CocoaPods only); Gitea job keeps cirruslabs 3.44.0 as base image
  (images discontinued) and switches the bundled Flutter SDK by git tag

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.gitea/workflows/build-apk.yaml

@@ -14,6 +14,10 @@ on:
       - master
   workflow_dispatch:
 
+env:
+  # Keep in sync with .github/workflows/build-ios.yaml and pubspec.yaml (environment).
+  FLUTTER_VERSION: '3.47.4'
+
 jobs:
   build-android:
     name: Build Release APKs
@@ -21,17 +25,36 @@ jobs:
     permissions:
       contents: write
     container:
-      image: ghcr.io/cirruslabs/flutter:3.24.5
+      # Cirrus Labs stopped publishing Flutter images in May 2026 (last tag: 3.44.0,
+      # multi-arch amd64/arm64, Ubuntu 24.04, OpenJDK 21, Android SDK 36). The image is
+      # only used for its JDK + Android SDK; the bundled Flutter SDK is switched to
+      # FLUTTER_VERSION in the first step.
+      image: ghcr.io/cirruslabs/flutter:3.44.0
       options: --privileged
     steps:
+      - name: Switch Flutter SDK to pinned version
+        run: |
+          set -euo pipefail
+          FLUTTER_ROOT="${FLUTTER_ROOT:-/sdks/flutter}"
+          git config --global --add safe.directory "$FLUTTER_ROOT"
+          git config --global --add safe.directory '*'
+          CURRENT="$(git -C "$FLUTTER_ROOT" describe --tags --exact-match 2>/dev/null || true)"
+          if [ "$CURRENT" != "$FLUTTER_VERSION" ]; then
+            echo "Switching Flutter SDK from '${CURRENT:-unknown}' to '$FLUTTER_VERSION'"
+            git -C "$FLUTTER_ROOT" fetch --depth 1 origin "refs/tags/${FLUTTER_VERSION}:refs/tags/${FLUTTER_VERSION}"
+            git -C "$FLUTTER_ROOT" checkout -q "$FLUTTER_VERSION"
+            # Drop the cache of the previous version; the Dart SDK and the engine
+            # artifacts for the new version are downloaded on first use.
+            rm -rf "$FLUTTER_ROOT/bin/cache"
+          fi
+          flutter --version
+
       - name: Setup Node.js 20 & ARM64 Flutter Engine
         run: |
           ARCH=$(uname -m)
           if [ "$ARCH" = "aarch64" ] || [ "$ARCH" = "arm64" ]; then NODE_ARCH="arm64"; else NODE_ARCH="x64"; fi
           curl -fsSL "https://nodejs.org/dist/v20.18.0/node-v20.18.0-linux-${NODE_ARCH}.tar.gz" | tar -xzf - -C /usr/local --strip-components=1
           node --version
-          git config --global --add safe.directory "$GITHUB_WORKSPACE"
-          git config --global --add safe.directory '*'
 
           # On Linux ARM64, Flutter engine and Android AAPT2 need x86_64 emulation via QEMU.
           if [ "$ARCH" = "aarch64" ] || [ "$ARCH" = "arm64" ]; then
@@ -58,8 +81,10 @@ jobs:
             done
 
             flutter precache --android
-            for dir in /sdks/flutter/bin/cache/artifacts/engine/android-*; do
-              if [ -d "$dir/linux-x64" ]; then
+            # Flutter (still) only ships an x86_64 gen_snapshot for Linux hosts; wrap it
+            # with QEMU under the linux-arm64 path the tool expects.
+            for dir in "${FLUTTER_ROOT:-/sdks/flutter}"/bin/cache/artifacts/engine/android-*; do
+              if [ -d "$dir/linux-x64" ] && [ ! -x "$dir/linux-arm64/gen_snapshot" ]; then
                 mkdir -p "$dir/linux-arm64"
                 printf '#!/bin/sh\nSCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"\nexec %s -L /usr/x86_64-linux-gnu "$SCRIPT_DIR/../linux-x64/gen_snapshot" "$@"\n' "$QEMU_BIN" > "$dir/linux-arm64/gen_snapshot"
                 chmod +x "$dir/linux-arm64/gen_snapshot"