reply UX: bigger chip, click-to-scroll with highlight

- Reply chip: larger with border-l-4, bg tint, proper padding
- Reply context in messages: click to smooth-scroll to quoted message
- Quoted message flashes primary/10 bg for 1.5s on scroll
- Each message gets id="msg-{id}" for scroll targeting
- Reply context text bumped to 11px

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/colony/src/components/MessageItem.tsx

@@ -60,22 +60,36 @@ export function MessageItem({ message, replyTarget, onReply }: Props) {
   const cfg = TYPE_CONFIG[message.type] || TYPE_CONFIG.text;
   const meta = message.metadata as Record<string, string> | null;
 
+  function scrollToMessage(id: string) {
+    const el = document.getElementById(`msg-${id}`);
+    if (el) {
+      el.scrollIntoView({ behavior: "smooth", block: "center" });
+      el.classList.add("!bg-primary/10");
+      setTimeout(() => el.classList.remove("!bg-primary/10"), 1500);
+    }
+  }
+
   return (
     <div
+      id={`msg-${message.id}`}
       className={cn(
-        "group border-b border-border/50 border-l-4 transition-colors",
+        "group border-b border-border/50 border-l-4 transition-all duration-300",
         cfg.border,
         isAgent ? "bg-card" : "bg-background",
         "hover:bg-muted/30",
       )}
     >
-      {/* Reply context */}
+      {/* Reply context — click to scroll to quoted message */}
       {replyTarget && (
-        <div className="px-4 pt-1.5 text-[10px] text-muted-foreground flex items-center gap-1">
+        <button
+          type="button"
+          onClick={() => scrollToMessage(replyTarget.id)}
+          className="w-full text-left px-4 pt-2 pb-0.5 text-[11px] text-muted-foreground flex items-center gap-1.5 hover:text-foreground transition-colors"
+        >
           <span className="text-primary font-bold">^</span>
           <span className="font-bold">{replyTarget.user.display_name}</span>
-          <span className="truncate max-w-40 md:max-w-80 opacity-60">{replyTarget.content}</span>
-        </div>
+          <span className="truncate max-w-48 md:max-w-96 opacity-60">{replyTarget.content}</span>
+        </button>
       )}
 
       <div className="px-4 py-3 md:px-5 md:py-4">