[Feature]: Simplify Quick Start history navigation

[huyanxius]

Problem

The Quick Start history navigation occupies the page as a persistent sidebar and introduces visual weight that is inconsistent with the product surface.

Scope

Refine the history navigation into a lightweight left-side entry and contextual floating panel. Keep the main Quick Start canvas full-width and avoid modal-style treatment or page blur.

Acceptance criteria

• The Quick Start canvas remains full-width when history is closed.
• A left-side three-line control opens the history panel.
• The panel can be dismissed by clicking outside or pressing Escape.
• The panel uses the existing product design tokens for color, border, radius, shadow, and typography.
• No unrelated pages or backend behavior are changed.