Adds intake_mode (bundled / separate / remote) so staff can mark
applications received with a single bundled PDF, the existing
separate-pages-file flow, or a pending remote signature. Folds in
content-based PDF validation, a friendlier status-gate message,
and a page-count helper for the original application.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
