Add safe offline queue recovery workflow

[stef-k]

Summary

• add a portable queue-recovery export using the existing idempotency GUID
• persistently suspend delivery and wait for active work before producing a recovery snapshot
• serialize Prepare, CSV/GeoJSON export, and Resume through one recovery-operation owner
• resume through the ordinary drain path so imported records reconcile without duplicates
• preserve Timeline import as local-history-only and never clear queue rows because of export/import
• document full phone-and-server recovery, expedited delivery, failure behavior, formats, and privacy

Coordinates with backend PR stef-k/Wayfarer#494.

Closes #244.

Validation

• final focused recovery safety/contracts: 12 passed
• focused affected recovery selection: 68 passed
• complete mobile suite before the final bounded coordination correction: 1,880 passed
• Release test/Core build: succeeded
• Android Release build: succeeded with existing package/XAML warnings
• git diff --check: passed

User workflow

Full recovery requires importing the recovery file into both:

1. the replacement phone Timeline for local history
2. Wayfarer for confirmed server history

Resume and reconcile then uses the normal drain path and the same idempotency GUID. Export never deletes queue records.

Database

No mobile schema migration.

[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
WayfarerMobile.Core	86%	79%	891	✔
Summary	86% (1181 / 1370)	79% (602 / 764)	891	✔