merge: resolve conflicts with main branch (keep both SharePoint + iCloud integrations)

Merge origin/main into copilot/add-sharepoint-integration.
All four conflicts were resolved by keeping both the SharePoint
additions (from this branch) and the iCloud additions (from main):
- app/models.py: added both SHAREPOINT and ICLOUD to IntegrationType
- app/tasks/send_to_all.py: added both to service_map and services list
- app/tasks/upload_to_user_integration.py: kept both upload handlers
- frontend/templates/files.html: added both filter options

No database migration conflicts — SharePoint does not require schema changes.

docs/StorageArchitecture.md

@@ -349,6 +349,7 @@ in task messages or logs.
 | `PAPERLESS`     | Paperless-ngx REST API, API token |
 | `EMAIL`         | SMTP/STARTTLS, file as attachment |
 | `RCLONE`        | `rclone copyto` subprocess, per-user rclone config |
+| `ICLOUD`        | pyicloud library, Apple ID + app-specific password |
 
 ### Multiple Destinations