perf(android): R8, bitmap downscaling, edge-to-edge; recover device compat; publish to production

Device compatibility (regression fix):
- The CAMERA permission (from zxing_barcode_scanner / image_picker) implicitly
  required android.hardware.camera, excluding camera-less devices — Play showed
  Automotive -96%, Chromebook -86%, TV -25%. Declare camera & location
  uses-feature required="false" to keep those devices supported.
- Detect a real camera at runtime (PackageManager.FEATURE_CAMERA_ANY via the
  existing MethodChannel), cache it at bootstrap, and hide the QR scan button and
  the camera photo-source option when absent, so no broken actions are offered.

Play "app optimization" recommendations:
- Enable R8 (isMinifyEnabled + isShrinkResources) with keep rules for the
  OCR (tesseract4android), SQLCipher and notifications JNI/reflection code.
- Bitmap downscaling: cacheWidth/cacheHeight (and ResizeImage for avatars) on
  list thumbnails and avatars so photos decode to on-screen size, not full res.
- Edge-to-edge: opt in with transparent system bars in main().

Release flow:
- Tagged builds now publish to the production track at 100% (was internal);
  add a manual deploy_internal lane as a QA safety net.
- Document country/region availability as a Play Console setting (not in-repo).

apps/app_seeds/lib/services/camera_availability.dart

@@ -0,0 +1,35 @@
+import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart';
+
+/// Whether this device has any camera. Resolved once at startup (via the native
+/// channel, `PackageManager.FEATURE_CAMERA_ANY`) and cached so `build()` methods
+/// can read it synchronously — the QR scan button ([qrScanSupported]) and the
+/// photo-source sheet hide their camera options when it is false.
+///
+/// Defaults to `true` so a normal phone never loses camera UI over a transient
+/// channel error; only genuinely camera-less devices (Chromebooks, Android
+/// Automotive, some TVs — kept installable by the `uses-feature required=false`
+/// in AndroidManifest) flip it to false. Non-Android platforms keep the default
+/// (iOS devices have a camera; desktop/web gate camera UI elsewhere).
+bool _deviceHasCamera = true;
+
+bool get deviceHasCamera => _deviceHasCamera;
+
+@visibleForTesting
+set deviceHasCamera(bool value) => _deviceHasCamera = value;
+
+const _channel = MethodChannel('org.comunes.tane/coarse_location');
+
+/// Queries the native camera-presence check and caches it. Called once during
+/// bootstrap, before the first real frame, so synchronous readers see the right
+/// value. Android-only; elsewhere the default stands. Never throws — a channel
+/// error leaves the safe default in place.
+Future<void> initCameraAvailability() async {
+  if (defaultTargetPlatform != TargetPlatform.android) return;
+  try {
+    final has = await _channel.invokeMethod<bool>('hasCamera');
+    if (has != null) _deviceHasCamera = has;
+  } catch (_) {
+    // Keep the default; a normal phone shouldn't lose camera UI over this.
+  }
+}