fix: serve uploaded images via API route (public/ is read-only in production)

Next.js bakes public/ at build time — dynamically uploaded files were
never served in Docker standalone mode. Store uploads in data/uploads/
and serve via /api/uploads/ with a rewrite for backward compatibility.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

memento-note/lib/ai/tools/extract-images.ts

@@ -10,7 +10,7 @@ import path from 'path'
 import { randomUUID } from 'crypto'
 import sharp from 'sharp'
 
-const UPLOADS_DIR = 'public/uploads/notes'
+const UPLOADS_DIR = 'data/uploads/notes'
 const URL_PREFIX = '/uploads/notes'
 const MAX_IMAGES_PER_PAGE = 3
 const MIN_IMAGE_SIZE = 200 // px -- skip icons, spacers, tracking pixels