fix(chat): conversation column widens to 64rem instead of 48rem

A wide pane left the chat squeezed into a 768px column with empty space
either side, so a wide table was cut off. The message list, the prompt
box and the session replay now share max-w-5xl.

client/src/components/conversation/MessageList.tsx

@@ -865,7 +865,7 @@ function MessageListView({
           className={
             compact
               ? "space-y-3 py-1 pr-2"
-              : "mx-auto flex w-full max-w-3xl flex-col gap-3 px-4 py-6"
+              : "mx-auto flex w-full max-w-5xl flex-col gap-3 px-4 py-6"
           }
         >
           {items.map((item) => {

client/src/components/lanes/SessionReplay.tsx

@@ -145,7 +145,7 @@ export function SessionReplay({
       {livePane ? (
         <div
           data-testid="session-replay-live"
-          className="mx-auto flex w-full max-w-3xl items-center gap-2 rounded-2xl border border-border p-3 text-xs text-fg-secondary"
+          className="mx-auto flex w-full max-w-5xl items-center gap-2 rounded-2xl border border-border p-3 text-xs text-fg-secondary"
         >
           <span className="min-w-0 flex-1">{t("replay.live")}</span>
           <button
@@ -160,7 +160,7 @@ export function SessionReplay({
       ) : session && !resumable ? (
         <div
           data-testid="session-replay-no-resume"
-          className="mx-auto flex w-full max-w-3xl items-center gap-2 rounded-2xl border border-border p-3 text-xs text-fg-secondary"
+          className="mx-auto flex w-full max-w-5xl items-center gap-2 rounded-2xl border border-border p-3 text-xs text-fg-secondary"
         >
           <span className="min-w-0 flex-1">{t("replay.noResume", { tool })}</span>
           <button
@@ -172,7 +172,7 @@ export function SessionReplay({
           </button>
         </div>
       ) : (
-        <div className="mx-auto w-full max-w-3xl rounded-2xl border border-border p-2 shadow-sm transition-colors focus-within:border-accent/50">
+        <div className="mx-auto w-full max-w-5xl rounded-2xl border border-border p-2 shadow-sm transition-colors focus-within:border-accent/50">
           <PromptEditor
             bare
             images={images}

client/src/components/run/PaneChat.tsx

@@ -858,7 +858,7 @@ export const PaneChat = memo(function PaneChat({
           )}
         </div>
         <div className="mx-4">
-          <div className="mx-auto w-full max-w-3xl">
+          <div className="mx-auto w-full max-w-5xl">
             {menu && (
               <PaneMenuCard
                 // A new question starts with its field closed.