feat(claims): three-mode Application Received wizard

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>

fusion_claims/tests/__init__.py

@@ -1,3 +1,4 @@
 # -*- coding: utf-8 -*-
 
 from . import test_signed_pages_gate
+from . import test_application_received_wizard