feat: add collapsible thinking section for intermediate results

- ThinkingSection component with expand/collapse toggle
- Displays intermediate_result from stream in amber-styled panel
- Positioned below orchestration progress indicator
- Updates in real-time as new intermediate results arrive

Closes #9

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/routes/chat/+page.svelte

@@ -3,6 +3,7 @@
 	import MessageList from '$lib/components/MessageList.svelte';
 	import MessageInput from '$lib/components/MessageInput.svelte';
 	import OrchestrationProgress from '$lib/components/OrchestrationProgress.svelte';
+	import ThinkingSection from '$lib/components/ThinkingSection.svelte';
 	import { processRequest, OrchestratorError } from '$lib/services/orchestrator';
 	import { OrchestrationState } from '$lib/proto/llm_multiverse/v1/orchestrator_pb';
 
@@ -11,10 +12,12 @@
 	let error: string | null = $state(null);
 	let sessionId = $state(crypto.randomUUID());
 	let orchestrationState: OrchestrationState = $state(OrchestrationState.UNSPECIFIED);
+	let intermediateResult: string = $state('');
 
 	async function handleSend(content: string) {
 		error = null;
 		orchestrationState = OrchestrationState.UNSPECIFIED;
+		intermediateResult = '';
 
 		const userMessage: ChatMessage = {
 			id: crypto.randomUUID(),
@@ -37,6 +40,9 @@
 		try {
 			for await (const response of processRequest(sessionId, content)) {
 				orchestrationState = response.state;
+				if (response.intermediateResult) {
+					intermediateResult = response.intermediateResult;
+				}
 				const idx = messages.length - 1;
 				messages[idx] = {
 					...messages[idx],
@@ -69,6 +75,7 @@
 
 	{#if isStreaming}
 		<OrchestrationProgress state={orchestrationState} />
+		<ThinkingSection content={intermediateResult} />
 	{/if}
 
 	{#if isStreaming && messages.length > 0 && messages[messages.length - 1].content === ''}