[Enhancement] Add a Reference of Original Sales Estimate in Converted Invoices

[anuj-ever]

Issue:

Currently, when a sales estimate is converted to a sales invoice, there is no reference back to the original estimate. This makes it difficult for users to trace the payment back to its initial proposal, causing potential confusion and gaps in the audit trail.

Expected Condition:

When a sales estimate is converted to a sales invoice, there should be a clear reference back to the original sales estimate. This will allow users to easily trace payments and understand the history of the transaction, ensuring comprehensive documentation and better financial tracking.

Supporting Document:

[samuelmbabhazi]

@anuj-ever can we have clear expectations for this please !

cc: @evereq

[anuj-ever]

@samuelmbabhazi As a user, if we can save the original sale estimate number/reference, when a sales estimate is converted to a sales invoice.

When converting a sales estimate to a sales invoice, the system should automatically save the original estimate number/reference in the invoice. This can be done through custom fields or database modifications. The user interface should auto-fill the estimate reference number in the invoice form, and reporting should link estimates to corresponding invoices for better traceability and accountability.