feat(skills): add color-palette generator skill

[muratclk]

Summary

Adds a new Color Palette Generator featured skill that lets users describe a mood, theme, or aesthetic and get a beautifully rendered 5-color palette card as an image.

How it works

1. User describes a mood/theme (e.g., "ocean sunset", "cozy coffee shop")
2. The on-device model selects 5 harmonious colors with creative names
3. The run_js tool renders a visual palette card on canvas with:
   • A titled header bar
   • 5 color swatches
   • Hex codes and color names below each swatch
4. Returns both the image and structured color data

Files added

• skills/featured/color-palette/SKILL.md — Skill definition with instructions and payload format
• skills/featured/color-palette/scripts/index.html — Canvas-based palette renderer

Design choices

• No external API or secret required — runs entirely on-device
• Uses HTML5 Canvas for clean, shareable image output
• Follows the same ai_edge_gallery_get_result pattern as existing skills (qr-code, mood-music)
• Apache 2.0 license header included

Test plan

• Install skill via the Gallery app's "Load skill from URL" feature
• Ask the model for palettes with various themes (sunset, forest, minimalist, retro)
• Verify the rendered image shows 5 color swatches with correct hex codes and names
• Test edge cases: very long color names, special characters in title

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