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/ui/variety_detail_screen.dart

@@ -2244,10 +2244,16 @@ class _PhotoGalleryState extends State<_PhotoGallery> {
                 itemBuilder: (_, i) => GestureDetector(
                   key: Key('photo.thumb.$i'),
                   onTap: () => _openPhotoViewer(context, cubit, i),
+                  // Decode to the 140px thumbnail size (× dpr), not full photo
+                  // resolution — the full-res decode happens in the viewer.
                   child: Image.memory(
                     photos[i].bytes,
                     width: 140,
                     height: 140,
+                    cacheWidth:
+                        (140 * MediaQuery.devicePixelRatioOf(context)).round(),
+                    cacheHeight:
+                        (140 * MediaQuery.devicePixelRatioOf(context)).round(),
                     fit: BoxFit.cover,
                   ),
                 ),