refactor(baoyu-article-illustrator): extract palette as independent third dimension

- Create palettes/ directory with macaron, warm, neon palette files
- Move macaron from styles/ to palettes/ (color scheme, not rendering style)
- Extract warm palette variant from vector-illustration into shared palette
- Add neon palette extracted from retro style colors
- Update architecture from Type × Style to Type × Style × Palette
- Add Palette Gallery and override rules to styles.md
- Add Palette Override section to prompt-construction.md
- Update presets table with Palette column
- Add palette selection step to workflow
- Add preferred_palette to EXTEND.md schema

skills/baoyu-article-illustrator/references/prompt-construction.md

@@ -135,10 +135,10 @@ COLORS: Cream background (#F5F0E6), Coral Red (#E07A5F), Mint Green (#81B29A), M
 ELEMENTS: Geometric simplified icons, no gradients, playful decorative elements (dots, stars)
 ```
 
-**Infographic + vector-illustration (warm palette)**:
+**Infographic + vector-illustration + warm palette**:
 ```
 Flat vector illustration infographic. Clean black outlines on all elements.
-Warm-only color palette, no cool colors.
+PALETTE OVERRIDE (warm): Warm-only color palette, no cool colors.
 COLORS: Soft Peach background (#FFECD2), Warm Orange (#ED8936),
         Terracotta (#C05621), Golden Yellow (#F6AD55), Deep Brown (#744210)
 ELEMENTS: Geometric simplified icons, no gradients, rounded corners,
@@ -207,10 +207,10 @@ COLORS: Left side Coral (#E07A5F), Right side Mint (#81B29A), cream background
 ELEMENTS: Bold icons, black outlines, centered divider line
 ```
 
-**Comparison + vector-illustration (warm palette)**:
+**Comparison + vector-illustration + warm palette**:
 ```
 Flat vector comparison with split layout. Clear visual separation.
-Warm-only color palette, no cool colors.
+PALETTE OVERRIDE (warm): Warm-only color palette, no cool colors.
 COLORS: Left side Warm Orange (#ED8936), Right side Terracotta (#C05621),
         Soft Peach background (#FFECD2), Deep Brown (#744210) accents
 ELEMENTS: Bold icons, black outlines, centered divider line
@@ -239,10 +239,10 @@ COLORS: Cream background (#F5F0E6), nodes in Coral/Mint/Mustard/Blue, black outl
 ELEMENTS: Rounded rectangles or circles for nodes, thick connecting lines
 ```
 
-**Framework + vector-illustration (warm palette)**:
+**Framework + vector-illustration + warm palette**:
 ```
 Flat vector framework diagram with geometric nodes and bold connectors.
-Warm-only color palette, no cool colors.
+PALETTE OVERRIDE (warm): Warm-only color palette, no cool colors.
 COLORS: Soft Peach background (#FFECD2), nodes in Warm Orange (#ED8936),
         Terracotta (#C05621), Golden Yellow (#F6AD55), black outlines
 ELEMENTS: Rounded rectangles or circles for nodes, thick connecting lines
@@ -264,37 +264,6 @@ STYLE: [style characteristics]
 ASPECT: 16:9
 ```
 
-### Macaron Style Instructions
-
-When `style: macaron`, add these style instructions:
-
-```
-Educational infographic with soft macaron pastel color blocks on warm cream paper.
-COLORS: Warm Cream background (#F5F0E8), Macaron Blue (#A8D8EA), Macaron Mint (#B5E5CF),
-        Macaron Lavender (#D5C6E0), Macaron Peach (#FFD5C2), Coral Red (#E8655A) for emphasis,
-        Deep Charcoal (#2D2D2D) text, Warm Gray (#6B6B6B) annotations
-CONTAINERS: Rounded cards, bubbles, dashed-box frames with pastel fills to separate info zones
-TYPOGRAPHY: Bold large title, bold keywords, smaller muted annotations
-STRUCTURE: Auto-select best layout for content (flow→arrows, compare→columns, cycle→ring, cards→grid)
-BOTTOM: Bold summary quote at bottom capturing core insight
-```
-
-**Infographic + macaron**:
-```
-Educational infographic on warm cream paper (#F5F0E8). Soft macaron pastel blocks as info zones.
-COLORS: Macaron Blue (#A8D8EA), Mint (#B5E5CF), Lavender (#D5C6E0), Peach (#FFD5C2),
-        Coral Red (#E8655A) for key data, Deep Charcoal (#2D2D2D) text
-ELEMENTS: Rounded-corner cards with pastel fills, clear labels, bold title, summary quote at bottom
-```
-
-**Flowchart + macaron**:
-```
-Process flow on warm cream paper (#F5F0E8). Each step in a macaron pastel card.
-COLORS: Steps alternate Macaron Blue (#A8D8EA), Mint (#B5E5CF), Lavender (#D5C6E0), Peach (#FFD5C2),
-        Coral Red (#E8655A) for decision points, Deep Charcoal (#2D2D2D) outlines
-ELEMENTS: Rounded step containers, soft arrow connectors, bold step labels
-```
-
 ### Screen-Print Style Override
 
 When `style: screen-print`, replace standard style instructions with:
@@ -327,6 +296,39 @@ TEXTURE: Halftone transitions between sides
 
 ---
 
+## Palette Override
+
+When a palette is specified (via `--palette` or preset), it overrides the style's default colors:
+
+1. Read style file → get rendering rules (Visual Elements, Style Rules, line treatment)
+2. Read palette file (`palettes/<palette>.md`) → get Colors + Background
+3. Palette Colors **replace** style's default Color Palette in prompt
+4. Palette Background **replaces** style's Background color (keep style's texture description)
+5. Build prompt: style rendering instructions + palette colors
+
+**Prompt frontmatter** includes palette when specified:
+```yaml
+---
+illustration_id: 01
+type: infographic
+style: vector-illustration
+palette: macaron
+---
+```
+
+**Example**: `vector-illustration` + `macaron` palette:
+```
+Flat vector illustration infographic. Clean black outlines on all elements.
+PALETTE: macaron — soft pastel color blocks
+COLORS: Warm Cream background (#F5F0E8), Macaron Blue (#A8D8EA), Mint (#B5E5CF),
+        Lavender (#D5C6E0), Peach (#FFD5C2), Coral Red (#E8655A) for emphasis
+ELEMENTS: Geometric simplified icons, no gradients, playful decorative elements
+```
+
+When no palette is specified, use the style's built-in Color Palette as before.
+
+---
+
 ## What to Avoid
 
 - Vague descriptions ("a nice image")