feat: click-only prototype walker — zero reloads, smooth Figma transitions

Rewrites the simulator to navigate entirely by clicks after a single
initial page.goto(). Uses DFS with page.goBack() for backtracking.

Key changes:
- Single page load, all subsequent navigation via mouse clicks
- Offset detection with retry for canvas coordinate mapping
- Banner dismissal via addInitScript CSS injection
- 800x1100 viewport with scaling=contain
- Tracks clicked edges to avoid re-clicking same destination
- Uses page.goBack() for backtracking (smooth Figma transition)
- Debug screenshot saved when recordDir is set

Verified: clicks produce native Figma transitions (overlay animations,
screen transitions) with zero white flashes or Figma loader between screens.

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

Author: oxxo