add automated screenshots, fastlane metadata, and appstream metainfo

Fixes #174, fixes #173, fixes #172

lib/widgets/account_scope.dart

@@ -1,5 +1,6 @@
 import "package:flutter_hooks/flutter_hooks.dart";
 import "package:flutter_riverpod/flutter_riverpod.dart";
+import "package:flutter_riverpod/misc.dart";
 import "package:material_ui/material_ui.dart";
 import "package:nexus/controllers/active_account.dart";
 import "package:nexus/controllers/notification_request.dart";
@@ -11,6 +12,9 @@ class const AccountScope({
   required final Widget child,
   final List<ProviderObserver>? observers,
   final Duration? Function(int retryCount, Object error)? retry,
+
+  /// Applied to each account's scope, after its own, e.g. for test fakes
+  final List<Override> overrides = const [],
   super.key,
 }) extends HookWidget {
   @override
@@ -34,6 +38,7 @@ class const AccountScope({
         NotificationRequestController.provider.overrideWithBuild(
           (_, _) => active.value.notificationRowId,
         ),
+        ...overrides,
       ],
       child: child,
     );

lib/widgets/avatars/avatar_or_hash.dart

@@ -12,9 +12,18 @@ final class const AvatarOrHash(
 }) extends ConsumerWidget {
   @override
   Widget build(BuildContext context, WidgetRef ref) {
+    final color = ColorHash(title).color;
     final box = ColoredBox(
-      color: ColorHash(title).color,
-      child: Center(child: Icon(Icons.person, size: dimension / 2)),
+      color: color,
+      child: Center(
+        child: Icon(
+          Icons.person,
+          size: dimension / 2,
+          color: ThemeData.estimateBrightnessForColor(color) == .dark
+              ? Colors.white
+              : Colors.black,
+        ),
+      ),
     );
 
     return SizedBox(

lib/widgets/users/user_span.dart

@@ -10,28 +10,32 @@ import "package:nexus/models/event.dart";
 
 /// A user's [name] in text, opening their popover when tapped. Unlike a widget
 /// in text, it wraps and ellipsizes with the rest of it.
-class UserSpan extends TextSpan {
-  UserSpan(
-    BuildContext context,
-    String name, {
-    required String userId,
-    required TapGestureRecognizer recognizer,
-    String? roomId,
-    super.style,
-    super.children,
-  }) : super(
-         text: name,
-         recognizer: recognizer
-           ..onTapUp = (details) {
-             if (!context.mounted) return;
 
-             context.showUserPopover(
-               userId,
-               roomId: roomId,
-               anchor: context.globalRectAt(details.globalPosition),
-             );
-           },
-       );
+// Can't be const, since it sets the recognizer's onTapUp
+// ignore: prefer_const_constructors_in_immutables
+class UserSpan(
+  BuildContext context,
+  String name, {
+  required String userId,
+  required TapGestureRecognizer recognizer,
+  String? roomId,
+  super.style,
+  super.children,
+}) extends TextSpan {
+  this
+    : super(
+        text: name,
+        recognizer: recognizer
+          ..onTapUp = (details) {
+            if (!context.mounted) return;
+
+            context.showUserPopover(
+              userId,
+              roomId: roomId,
+              anchor: context.globalRectAt(details.globalPosition),
+            );
+          },
+      );
 
   factory UserSpan.sender(
     BuildContext context,