macOS VibeBar design system

[bukeke111]

Motivation

• Provide a reusable, platform-aligned design system for the macOS VibeBar / 刘海 Island feature that maps Apple HIG (Live Activities, Dynamic Island, Widgets, Typography, Buttons) to a desktop-first visual language.
• Standardize colors, typography, spacing, components and motion so front-end and design teams can implement a consistent Floating System Status Surface on macOS.
• Improve discoverability by surfacing the spec from the repository architecture documentation.

Description

• Add a new design spec at docs/design/mac-vibebar-design-system.md that defines visual language, color tokens (island black, semantic accents), typography (SF Pro / PingFang SC / SF Mono), spacing (4pt grid), radii, shadow/highlight rules, motion timings, components (Capsule Island, Expanded Panel, Status Chip, AI Task Card) and interaction/acceptance guidelines.
• Link the new spec from docs/architecture.md under a new "设计规范" section for discoverability.
• Include concrete tokens and implementation-friendly rules for collapsed/expanded layouts, button/input sizes and accessibility hit areas to support direct translation to Figma/SF Symbols/SwiftUI tokens.

Testing

• Ran git diff --check and a small Python validation script that verifies required sections are present; initial run failed due to a missing "整体" keyword check and the document title was adjusted accordingly.
• Re-ran git diff --check and the Python validation script after the fix, and both checks passed.
• Verified repository status shows the expected documentation changes staged and committed (working tree clean) after tests passed.

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Codex Task