Critical fixes:
- Sibling matching now requires BOTH request_number AND search_scope
(previously matched on request_number alone, mixing different people)
- If page 2 has no search_scope, inheritance is skipped (safe default)
- Inherit search_scope from sibling doc during confirm so merge validation works
- Normalize scope values on both sides when checking merge_allowed
- Merge was blocked because page 2 had empty search_scope, making same_scope always false
- Detect page 2+ from page_info field (e.g. صفحة ٢ من 5) with Arabic digit support
- Find sibling documents by matching request_number, not just pdf_group_id
- Works for both PDF splits AND individually photographed pages
- Inherit all person fields (name, father, family, registry, etc.) from confirmed sibling
- Update review banner to show for all subsequent pages
- Move first_name validation after document load so page 2+ can inherit
- Resolve page 1's confirmed person and auto-fill name/father/family/registry
- Fixes 'First name is required' error on subsequent PDF pages
- Add stage/process-staged/remove-staged endpoints for batch upload workflow
- Add staging gallery UI with thumbnail previews and per-image removal
- Inherit person info & doc fields from page 1 for multi-page PDFs
- Auto-link page 2+ to same person on confirmation
- Show info banner on review page for multi-page documents
- Exclude staged docs from stats counters