Initial release: swift-front skill with Apple HIG integration

Combines frontend-design aesthetics with swiftui-pro correctness,
grounded in Apple's Human Interface Guidelines (134 articles).

Includes curated HIG reference files for typography, color, layout,
materials, motion, icons, and components, plus full HIG JSON data
for deep lookups.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

references/hig-color.md

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+# HIG: Color & Dark Mode
+
+Source: [Apple HIG — Color](https://developer.apple.com/design/human-interface-guidelines/color) | [Dark Mode](https://developer.apple.com/design/human-interface-guidelines/dark-mode)
+
+## Best Practices
+
+- Don't use the same color to mean different things — use color consistently for status and interactivity
+- All colors must work in light, dark, AND increased contrast contexts
+- Even single-appearance apps must provide both light and dark colors for Liquid Glass adaptivity
+- Test colors under different lighting conditions (bright sunlight, dim light)
+- Test on multiple devices (True Tone displays adapt white point)
+- Avoid hard-coding system color values — use `Color` API
+- Use wide color (Display P3) for richer, more saturated colors on compatible displays
+- Use asset catalog Color Sets with light/dark variants
+
+## Inclusive Color
+
+- Never rely solely on color to differentiate objects or communicate info
+- Provide text labels, glyph shapes, or patterns as alternatives
+- Ensure sufficient contrast so icons and text don't blend with background
+- Consider cultural color meanings (red = danger in some cultures, positive in others)
+
+## System Colors (SwiftUI)
+
+red, orange, yellow, green, mint, teal, cyan, blue, indigo, purple, pink, brown
+
+- visionOS uses default dark color values
+- iOS/iPadOS has 6 system grays: `gray` (SwiftUI) = `systemGray` (UIKit), plus `systemGray2`-`systemGray6`
+
+## iOS/iPadOS Dynamic Background Colors
+
+Two sets — **system** and **grouped** — each with primary, secondary, tertiary:
+
+| Level | Use for |
+|-------|---------|
+| Primary | Overall view background |
+| Secondary | Grouping content within the overall view |
+| Tertiary | Grouping content within secondary elements |
+
+Use **grouped** set with grouped table views; **system** set otherwise.
+
+## Foreground Colors (iOS)
+
+| Color | Use | UIKit API |
+|-------|-----|-----------|
+| Label | Primary content text | `label` |
+| Secondary label | Secondary content | `secondaryLabel` |
+| Tertiary label | Tertiary content | `tertiaryLabel` |
+| Quaternary label | Quaternary content | `quaternaryLabel` |
+| Placeholder text | Control placeholders | `placeholderText` |
+| Separator | Allows underlying content through | `separator` |
+| Opaque separator | Fully opaque | `opaqueSeparator` |
+| Link | Hyperlink text | `link` |
+
+## Liquid Glass Color
+
+- Liquid Glass has no inherent color — takes on colors from content behind it
+- Apply color sparingly — reserve for emphasis (status indicators, primary actions)
+- For primary actions, color the background (not symbols/text)
+- Don't apply color to multiple control backgrounds
+- Symbols/text on Liquid Glass can have color (e.g., selected tab bar item)
+- Avoid similar colors in control labels over colorful backgrounds — prefer monochromatic
+
+## Color Management
+
+- Apply color profiles to images (sRGB for most, Display P3 for wide color)
+- Wide color: P3 profile at 16 bits/channel, export as PNG
+- Provide color space-specific variants if P3 gradients appear clipped on sRGB displays
+
+## Dark Mode
+
+- Don't offer app-specific appearance toggle — respect system setting
+- Ensure content is legible in both modes, including with Increase Contrast + Reduce Transparency
+- Dark palette uses dimmer backgrounds, brighter foregrounds (not simple inversions)
+- Use semantic Color Set assets with light/dark variants — avoid hard-coded values
+- Minimum contrast ratio: 4.5:1; aim for 7:1 especially in small text
+- Soften white backgrounds slightly to prevent glowing in dark contexts
+
+### iOS/iPadOS Dark Mode
+
+- Two background levels: **base** (dimmer, recedes) and **elevated** (brighter, advances)
+- System auto-switches base to elevated for popovers, modal sheets, foreground apps
+- Use system background colors to maintain these visual distinctions
+
+### macOS Dark Mode
+
+- Desktop tinting: window backgrounds pick up color from desktop picture (graphite accent)
+- Add transparency to custom component backgrounds (neutral state only) for tinting harmony
+
+## Platform-Specific Notes
+
+- **tvOS:** Limited color palette coordinating with app logo; don't use only color to indicate focus
+- **visionOS:** Use color sparingly on glass; prefer bold text/large areas; keep brightness balanced
+- **watchOS:** Background color should communicate, not just decorate; avoid full-screen background color in long-duration views