- Add npcAvatars storage to extension settings for custom NPC images
- Implement getCharacterAvatar() to check custom avatars first
- Add uploadNpcAvatar() function with file validation (2MB max, images only)
- Make character avatars clickable with visual feedback
- Support left-click to upload and right-click to remove custom avatars
- Add camera icon overlay on hover with smooth animations
- Store avatars as base64 data URIs for persistence across sessions