fix(flutter_desktop): selection in AI chat going missing while scrolling (#7281)

frontend/appflowy_flutter/lib/plugins/ai_chat/chat_page.dart

@@ -121,14 +121,16 @@ class _ChatContentPage extends StatelessWidget {
                   child: Align(
                     alignment: Alignment.topCenter,
                     child: _wrapConstraints(
-                      ScrollConfiguration(
+                      SelectionArea(
+                        child: ScrollConfiguration(
                           behavior: ScrollConfiguration.of(context)
                               .copyWith(scrollbars: false),
                           child: Chat(
                             chatController:
                                 context.read<ChatBloc>().chatController,
                             user: User(id: userProfile.id.toString()),
-                          darkTheme: ChatTheme.fromThemeData(Theme.of(context)),
+                            darkTheme:
+                                ChatTheme.fromThemeData(Theme.of(context)),
                             theme: ChatTheme.fromThemeData(Theme.of(context)),
                             builders: Builders(
                               inputBuilder: (_) => const SizedBox.shrink(),
@@ -142,6 +144,7 @@ class _ChatContentPage extends StatelessWidget {
                       ),
                     ),
                   ),
+                ),
                 _wrapConstraints(
                   _builtInput(context),
                 ),

frontend/appflowy_flutter/lib/plugins/ai_chat/presentation/message/user_text_message.dart

@@ -83,7 +83,6 @@ class TextMessageText extends StatelessWidget {
       text,
       lineHeight: 1.4,
       maxLines: null,
-      selectable: true,
       color: AFThemeExtension.of(context).textColor,
     );
   }

frontend/appflowy_flutter/packages/flowy_infra_ui/lib/style_widget/text.dart

@@ -15,7 +15,6 @@ class FlowyText extends StatelessWidget {
   final TextDecoration? decoration;
   final Color? decorationColor;
   final double? decorationThickness;
-  final bool selectable;
   final String? fontFamily;
   final List<String>? fallbackFontFamily;
   final bool withTooltip;
@@ -41,7 +40,6 @@ class FlowyText extends StatelessWidget {
     this.maxLines = 1,
     this.decoration,
     this.decorationColor,
-    this.selectable = false,
     this.fontFamily,
     this.fallbackFontFamily,
     // // https://api.flutter.dev/flutter/painting/TextStyle/height.html
@@ -63,7 +61,6 @@ class FlowyText extends StatelessWidget {
     this.maxLines = 1,
     this.decoration,
     this.decorationColor,
-    this.selectable = false,
     this.fontFamily,
     this.fallbackFontFamily,
     this.lineHeight,
@@ -86,7 +83,6 @@ class FlowyText extends StatelessWidget {
     this.maxLines = 1,
     this.decoration,
     this.decorationColor,
-    this.selectable = false,
     this.fontFamily,
     this.fallbackFontFamily,
     this.lineHeight,
@@ -108,7 +104,6 @@ class FlowyText extends StatelessWidget {
     this.maxLines = 1,
     this.decoration,
     this.decorationColor,
-    this.selectable = false,
     this.fontFamily,
     this.fallbackFontFamily,
     this.lineHeight,
@@ -130,7 +125,6 @@ class FlowyText extends StatelessWidget {
     this.maxLines = 1,
     this.decoration,
     this.decorationColor,
-    this.selectable = false,
     this.fontFamily,
     this.fallbackFontFamily,
     this.lineHeight,
@@ -153,7 +147,6 @@ class FlowyText extends StatelessWidget {
     this.maxLines = 1,
     this.decoration,
     this.decorationColor,
-    this.selectable = false,
     this.lineHeight,
     this.withTooltip = false,
     this.strutStyle = const StrutStyle(forceStrutHeight: true),
@@ -211,16 +204,6 @@ class FlowyText extends StatelessWidget {
               : null,
         );
 
-    if (selectable) {
-      child = IntrinsicHeight(
-        child: SelectableText(
-          text,
-          maxLines: maxLines,
-          textAlign: textAlign,
-          style: textStyle,
-        ),
-      );
-    } else {
     child = Text(
       text,
       maxLines: maxLines,
@@ -236,7 +219,6 @@ class FlowyText extends StatelessWidget {
             )
           : null,
     );
-    }
 
     if (withTooltip) {
       child = FlowyTooltip(