fix(sessions): strip OpenClaw message_id suffix and allow 2-line titles

OpenClaw gateway injects `[message_id: UUID]` metadata at the end of
every message, wasting display space. Strip this suffix from both title
and summary fields.

Also change session title display from single-line truncate to
line-clamp-2, so longer titles (e.g. OpenClaw's timestamp-prefixed
messages) can show more meaningful content across two lines.

src/components/sessions/SessionItem.tsx

@@ -85,7 +85,7 @@ export function SessionItem({
               {getProviderLabel(session.providerId, t)}
             </TooltipContent>
           </Tooltip>
-          <span className="text-sm font-medium truncate flex-1">
+          <span className="text-sm font-medium line-clamp-2 flex-1">
             {searchQuery ? highlightText(title, searchQuery) : title}
           </span>
           <ChevronRight