fix: use UTC timezone in formatTime to fix CI test failure

formatTime used toLocaleTimeString without specifying timeZone, causing
timestamps to render differently in CI (UTC) vs local dev (UTC+1).
Added timeZone: 'UTC' and updated test assertion to match.

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

Author: acailic

frontend/src/__tests__/ToolInspector.test.tsx

@@ -45,7 +45,7 @@ describe('ToolInspector', () => {
     render(<ToolInspector event={event} />)
 
     expect(screen.getByText('tool-123')).toBeInTheDocument()
-    expect(screen.getByText(/11:00:00/)).toBeInTheDocument()
+    expect(screen.getByText(/10:00:00/)).toBeInTheDocument()
   })
 
   it('renders arguments section when arguments exist', () => {

frontend/src/utils/formatting.ts

@@ -7,6 +7,7 @@ export function formatTime(timestamp: string): string {
     minute: '2-digit',
     second: '2-digit',
     hour12: false,
+    timeZone: 'UTC',
   })
 }