implemented in-chat search with text highlighting, added search navigation UI, and integrated scrollable list for message jumping

lib/view/pages/talk/widgets/bubble.dart

@@ -27,6 +27,7 @@ class BubbleStyle {
   const BubbleStyle({
     this.color,
     this.borderWidth = 0,
+    this.borderColor,
     this.elevation = 0,
     this.margin = const BubbleEdges.only(),
     this.padding = const BubbleEdges.all(8),
@@ -37,12 +38,25 @@ class BubbleStyle {
 
   final Color? color;
   final double borderWidth;
+  final Color? borderColor;
   final double elevation;
   final BubbleEdges margin;
   final BubbleEdges padding;
   final Alignment alignment;
   final BubbleNip nip;
   final double borderRadius;
+
+  BubbleStyle copyWith({double? borderWidth, Color? borderColor}) => BubbleStyle(
+    color: color,
+    borderWidth: borderWidth ?? this.borderWidth,
+    borderColor: borderColor ?? this.borderColor,
+    elevation: elevation,
+    margin: margin,
+    padding: padding,
+    alignment: alignment,
+    nip: nip,
+    borderRadius: borderRadius,
+  );
 }
 
 /// The "nip" is faked by flattening one corner so the bubble anchors to
@@ -88,7 +102,7 @@ class Bubble extends StatelessWidget {
           borderRadius: radius,
           border: style.borderWidth > 0
               ? Border.all(
-                  color: Theme.of(context).dividerColor,
+                  color: style.borderColor ?? Theme.of(context).dividerColor,
                   width: style.borderWidth,
                 )
               : null,