- Add ProjectAllocationIn and allocations field to ItemDecisionIn schema
- Implement line item split allocation across projects in accept_quote
- Replicate all ItemTermsheet options and LineItemSpec records to split rows
- Ensure QuoteProjects and LineItemProjects relations are updated
- Add validation against duplicate project selection and decimal sum mismatches
- Implement _merge_split_line_items_on_reopen to consolidate rows when reverting status to offered