Create a [SIZE]x[SIZE] pixel art item/object sprite in pixelsrc JSONL format.

Item description:
- [DESCRIBE ITEM: sword, potion, key, chest, etc.]
- [DESCRIBE MATERIALS: wood, metal, glass, magical, etc.]
- [DESCRIBE STYLE: fantasy RPG, sci-fi, cute, realistic]

Requirements:
- Use semantic token names based on materials: {blade}, {hilt}, {gem}, {wood}, {metal}
- Include {_} mapped to #00000000 for transparent background
- Add {highlight} and {shadow} variants for depth
- Keep palette under 8 colors for clean retro look
- Center the item in the sprite frame

Output format:
1. Single line with inline palette in sprite definition
2. Ensure each grid row has exactly [SIZE] tokens
3. Use valid hex colors: #RRGGBB

Example structure:
{"type":"sprite","name":"[ITEM_NAME]","palette":{"{_}":"#00000000","{blade}":"#C0C0C0","{hilt}":"#8B4513"},"grid":["...",...]}

Visual guidelines:
- Use lighter colors on top-left for highlight (light source)
- Use darker colors on bottom-right for shadow
- Include an outline or edge color for definition
- Leave 1-2 pixel margin for breathing room
