ModelMeta.profile_image_url now runs validate_profile_image_url, rejecting SVG/script data URIs (matching UserUpdateForm and ChannelWebhookForm). The /model/profile/image endpoint enforces the PROFILE_IMAGE_ALLOWED_MIME_TYPES allowlist and sets X-Content-Type-Options: nosniff, so an SVG data URI can no longer be served inline on-origin. Closes the fourth profile-image XSS sink missed by the user and webhook fixes. Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>