Added new invoice status IN_COLLECTION plus queryset helpers .in_collection() and .not_in_collection() for filtering invoices currently in collection.
Improved MRP v2 export error handling: per-invoice XML validation failures no longer abort the whole export and are reported in the summary email, and fatal configuration errors mark the export as failed with a clear message.
Updated exporters (PDF, XLSX, ISDOC, MRP v1, MRP v2) and managers to align with the latest ExporterMixin API, using model/queryset fields and queryset-based validation; managers without required_origin now allow mixed-origin querysets.