fix(frontend): refine activity layout and input state

frontend/src/shell/ModelActivityPanel.tsx

@@ -10,6 +10,7 @@ const TAIL_PARAGRAPHS = 5;
 export function formatModelActivity(text: string): string {
   return text
     .replace(/\r\n?/g, "\n")
+    .replace(/([.!?])(?=[A-ZÀ-ÖØ-Þ])/g, "$1\n\n")
     .replace(/^[\t ]*[•‣–]\s+/gm, "- ")
     .replace(/^(\d+)\)\s+/gm, (_, n) => `${n}. `)
     .replace(/\n(?=\S)(?![-*+] |\d+\. |>|`|\|)/g, "\n\n")
@@ -40,7 +41,7 @@ export function ModelActivityPanel({ onClose }: { onClose: () => void }) {
   const source = formatModelActivity(shown.join("\n\n"));
 
   return (
-    <aside className="flex w-[30vw] max-w-[30vw] shrink-0 flex-col border-r border-border bg-sidebar">
+    <aside className="flex w-2/5 shrink-0 flex-col border-r border-border bg-sidebar">
       <div className="flex items-center justify-between border-b border-border/60 px-3 py-3">
         <h2 className="font-heading text-sm font-semibold text-foreground">Model activity</h2>
         <div className="flex items-center gap-1">