feat(baoyu-image-cards): add image card series skill migrated from baoyu-xhs-images

Rename baoyu-xhs-images to baoyu-image-cards to decouple from Xiaohongshu platform.
Deprecate baoyu-xhs-images with migration notice pointing to baoyu-image-cards.

skills/baoyu-image-cards/references/elements/image-effects.md

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+# Image Processing Layer
+
+Visual effects applied to image elements in Xiaohongshu infographics.
+
+## AI Cutout (抠图)
+
+Subject extraction styles for product/figure isolation.
+
+| Name | Description | Use Case |
+|------|-------------|----------|
+| clean | Sharp edges, precise boundaries | Product photography, tech items |
+| soft | Soft transition, feathered edges | Portrait cutout, organic subjects |
+| stylized | Hand-drawn edge treatment | Artistic compositions |
+
+## Stroke Effects (描边)
+
+Border treatments for cutout elements.
+
+| Name | Description | Use Case |
+|------|-------------|----------|
+| white-solid | White solid line border | Classic sticker feel, high contrast |
+| colored-solid | Colored solid line border | Playful vibe, brand colors |
+| dashed | Dashed/dotted border | Handmade aesthetic, casual |
+| double | Double-layer stroke | Emphasis effect, premium feel |
+| glow | Soft outer glow | Dreamy, soft aesthetic |
+| shadow | Drop shadow effect | Depth, floating element |
+
+**Stroke Width Guidelines**:
+- Thin: 2-4px - Subtle, elegant
+- Medium: 5-8px - Standard visibility
+- Thick: 10-15px - Bold emphasis
+
+## Filters (滤镜)
+
+Color grading and mood presets popular on XHS.
+
+| Name | Chinese | Description | Mood |
+|------|---------|-------------|------|
+| clear-glow | 清透感 | Transparent, radiant, luminous | Fresh, youthful |
+| film-grain | 胶片感 | Vintage film aesthetic, grain texture | Nostalgic, artistic |
+| cream-skin | 奶油肌 | Smooth, creamy complexion tones | Soft, flattering |
+| japanese-magazine | 日杂感 | Lifestyle magazine aesthetic | Curated, aspirational |
+| high-saturation | 高饱和 | Vibrant, punchy colors | Energetic, eye-catching |
+| muted-tones | 莫兰迪 | Morandi-style desaturated palette | Sophisticated, calm |
+| warm-tone | 暖色调 | Golden hour warmth | Cozy, inviting |
+| cool-tone | 冷色调 | Blue-shifted coolness | Modern, clean |
+
+## Texture Overlays
+
+Additional texture effects.
+
+| Name | Description | Use Case |
+|------|-------------|----------|
+| paper | Paper or fabric texture | Handmade feel |
+| noise | Fine grain noise | Analog aesthetic |
+| halftone | Dot pattern | Retro print style |
+| scratch | Light scratch marks | Vintage wear |
+
+## Blending Modes
+
+For layered compositions.
+
+| Mode | Effect | Use Case |
+|------|--------|----------|
+| multiply | Darken, merge | Shadow effects |
+| screen | Lighten, glow | Light effects |
+| overlay | Contrast boost | Vibrant compositions |
+| soft-light | Subtle blending | Natural layering |
+
+## Effect Combinations
+
+Common effect stacks for different styles:
+
+### Cute Style
+- Filter: clear-glow or cream-skin
+- Stroke: white-solid (medium)
+- Texture: none
+
+### Notion Style
+- Filter: none or muted-tones
+- Stroke: white-solid (thin) or none
+- Texture: paper (subtle)
+
+### Retro Style
+- Filter: film-grain
+- Stroke: double or dashed
+- Texture: halftone, scratch
+
+### Bold Style
+- Filter: high-saturation
+- Stroke: colored-solid (thick)
+- Texture: none