fix(status-line): guard messagesRef.current against null

messagesRef.current is typed as Message[] | null per React's RefObject.
doesMostRecentAssistantMessageExceed200k() and getCurrentUsage() expect
Message[], not null. Add ?? [] fallback to prevent runtime error.

Addresses CodeRabbit finding on PR #51.

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

Author: unraid

src/components/StatusLine.tsx

@@ -33,13 +33,13 @@ function StatusLineInner({ messagesRef, lastAssistantMessageId }: Props): React.
   const mainLoopModel = useMainLoopModel();
   const permissionMode = useAppState(s => s.toolPermissionContext.mode);
 
-  const exceeds200kTokens = lastAssistantMessageId
-    ? doesMostRecentAssistantMessageExceed200k(messagesRef.current)
-    : false;
+  const messages = messagesRef.current ?? [];
+
+  const exceeds200kTokens = lastAssistantMessageId ? doesMostRecentAssistantMessageExceed200k(messages) : false;
 
   const runtimeModel = getRuntimeMainLoopModel({ permissionMode, mainLoopModel, exceeds200kTokens });
   const modelDisplay = renderModelName(runtimeModel);
-  const currentUsage = getCurrentUsage(messagesRef.current);
+  const currentUsage = getCurrentUsage(messages);
   const contextWindowSize = getContextWindowForModel(runtimeModel, getSdkBetas());
   const contextPercentages = calculateContextPercentages(currentUsage, contextWindowSize);
   const rawUtil = getRawUtilization();