fix: make landing page animations more dramatic and noticeable

- Slower chat stagger (1.2s between lines, not 0.6s) so each message
  is clearly individual and watchable
- Messages slide in from left (translateX -20px) not just fade up
- Typing indicator is bigger with blue tinted background, border,
  and "FlowPilot is thinking..." label
- Typing indicator holds for 3s before collapsing (was 1.8s)
- App preview has cinematic entrance (scale 0.95 → 1 + translateY)
- AI responses wait until typing indicator finishes, then cascade
- Doc confirmation has extra pause before appearing (9.6s total)

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

frontend/src/pages/LandingPage.tsx

@@ -225,6 +225,7 @@ export default function LandingPage() {
                     <div className="landing-chat-animated" style={{ '--chat-index': 1 } as React.CSSProperties}>
                       <div className="landing-typing-indicator">
                         <span /><span /><span />
+                        <span style={{ fontSize: '0.55rem', color: '#60a5fa', marginLeft: 4, fontWeight: 500, whiteSpace: 'nowrap' }}>FlowPilot is thinking...</span>
                       </div>
                     </div>
                     <div className="landing-chat-animated" style={{ '--chat-index': 2 } as React.CSSProperties}>