Images were previously converted to markdown data URLs which Claude API
treats as plain text, not as actual images.
Changes:
- Add parseMessageWithAttachments() that returns {message, images[]}
- Pass images through the stack to session.prompt() as content blocks
- Filter null/empty attachments before parsing
- Strip data URL prefix if client sends it
This enables iOS and other clients to send images that Claude can actually see.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
