feat(app): streamline Ribbon and unify macOS title bar

[Limdongcheng]

Summary

• Merge the native macOS traffic lights and Ribbon task row into one unified top bar while preserving native window controls and system window semantics.
• Add a responsive inline project title, draggable chrome regions, and compact right-side controls without changing the existing Windows/Linux title bar.
• Remove the redundant persistent Context line below the Ribbon while retaining the bottom Status bar for hints, progress, and operation feedback.
• Keep compact Ribbon group captions such as Guides and Object on one line, and update the English and Simplified Chinese manuals.

Validation

• cargo pr-check
• npm run build in docs/ (71 pages)
• Dark-theme Ribbon screenshot scenarios at 720, 900, and 1440 pt widths
• Manual macOS preview checks for traffic-light clearance, task-tab alignment, project-title truncation, and compact group captions

UI display logic

• No new or changed actions; command catalog requirement is not applicable.
• Responsive hiding remains at Ribbon-group level; this change does not add transient action visibility.
• No layout changes from background events; panels are never auto-closed.
• No new panels or empty regions; empty-state requirement is not applicable.
• Docs updated in docs/ (English and zh-CN) for user-visible behavior.