fix(chat): remove loadHistory run completion inference, rely on Gateway events

loadHistory repeatedly set sending=false during server-side tool execution
by incorrectly inferring run completion from message content.

Run completion is now ONLY signalled by:
1. Gateway's phase 'completed' event (gateway.ts)
2. Streaming 'final' event (runtime-event-handlers.ts)
3. Safety timeout after 90s of no events

Also: fully controlled graph expanded prop, stable key, card.active
decoupled from streamingReplyText, suppressThinking prop.

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

src/pages/Chat/ExecutionGraphCard.tsx

@@ -8,6 +8,8 @@ interface ExecutionGraphCardProps {
   agentLabel: string;
   steps: TaskStep[];
   active: boolean;
+  /** Hide the trailing "Thinking ..." indicator even when active. */
+  suppressThinking?: boolean;
   /**
    * When provided, the card becomes fully controlled: the parent owns the
    * expand state (e.g. to persist across remounts) and toggling goes through
@@ -149,6 +151,7 @@ export function ExecutionGraphCard({
   agentLabel,
   steps,
   active,
+  suppressThinking = false,
   expanded: controlledExpanded,
   onExpandedChange,
 }: ExecutionGraphCardProps) {
@@ -175,7 +178,7 @@ export function ExecutionGraphCard({
 
   const toolCount = steps.filter((step) => step.kind === 'tool').length;
   const processCount = steps.length - toolCount;
-  const shouldShowTrailingThinking = active;
+  const shouldShowTrailingThinking = active && !suppressThinking;
 
   if (!expanded) {
     return (