Move email attachment uploads out of the workflow folder into a dedicated
EmailAttachment module with its own FileFolder, resolver, and service.
Add a 100-recipient cap (To+Cc+Bcc) enforced on both frontend and backend.
Extract shared AttachmentChip component for reuse across email and workflow.
Introduce a new "Open in app" click action for email fields that opens the
side-panel composer directly. This becomes the default for email fields.
When no connected account is available, it gracefully falls back to
mailto: instead of redirecting to settings.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
