Split message reaction tray from popover

Keep the message action popover below the mobile file-size ratchet by moving
the reaction tray wrapper into its own part file without changing behavior.

Co-authored-by: Carl <c7ebe626f000404285d3686e1dc74cc07cc60a9754a150041ba132e14bd3e2ec@buzz.block.builderlab.xyz>
Signed-off-by: Wes <wesbillman@users.noreply.github.com>

mobile/lib/features/channels/message_actions.dart

@@ -41,6 +41,7 @@ import 'timeline_message.dart';
 part 'message_actions/reaction_popover.dart';
 part 'message_actions/quick_reaction_row.dart';
 part 'message_actions/message_action_popover.dart';
+part 'message_actions/message_reaction_tray.dart';
 
 /// Preview length for reminder targets — matches desktop's
 /// `msg.body.slice(0, 100)`.

mobile/lib/features/channels/message_actions/message_action_popover.dart

@@ -810,41 +810,6 @@ class _LiftedMessagePreview extends StatelessWidget {
   }
 }
 
-class _MessageReactionTray extends StatelessWidget {
-  final Animation<double> animation;
-  final double trayWidth;
-  final TimelineMessage message;
-  final BuildContext pageContext;
-  final WidgetRef pageRef;
-  final Object popResult;
-  final void Function(Object? result, VoidCallback effect) onSelected;
-
-  const _MessageReactionTray({
-    required this.animation,
-    required this.trayWidth,
-    required this.message,
-    required this.pageContext,
-    required this.pageRef,
-    required this.popResult,
-    required this.onSelected,
-  });
-
-  @override
-  Widget build(BuildContext context) {
-    return _AnimatedReactionTray(
-      trayKey: const ValueKey('message-action-reaction-tray'),
-      animation: animation,
-      trayWidth: trayWidth,
-      scaleAlignment: Alignment.bottomLeft,
-      message: message,
-      pageContext: pageContext,
-      pageRef: pageRef,
-      popResult: popResult,
-      onSelected: onSelected,
-    );
-  }
-}
-
 class _MessageActionSurface extends StatelessWidget {
   final List<_PopoverMessageAction> actions;
   final ValueChanged<String> onSelected;

mobile/lib/features/channels/message_actions/message_reaction_tray.dart

@@ -0,0 +1,36 @@
+part of '../message_actions.dart';
+
+class _MessageReactionTray extends StatelessWidget {
+  final Animation<double> animation;
+  final double trayWidth;
+  final TimelineMessage message;
+  final BuildContext pageContext;
+  final WidgetRef pageRef;
+  final Object popResult;
+  final void Function(Object? result, VoidCallback effect) onSelected;
+
+  const _MessageReactionTray({
+    required this.animation,
+    required this.trayWidth,
+    required this.message,
+    required this.pageContext,
+    required this.pageRef,
+    required this.popResult,
+    required this.onSelected,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return _AnimatedReactionTray(
+      trayKey: const ValueKey('message-action-reaction-tray'),
+      animation: animation,
+      trayWidth: trayWidth,
+      scaleAlignment: Alignment.bottomLeft,
+      message: message,
+      pageContext: pageContext,
+      pageRef: pageRef,
+      popResult: popResult,
+      onSelected: onSelected,
+    );
+  }
+}