feat(transactions): generate default transfer memo for XFER_INTERNAL (#65)

[tswarren]

Summary

• Generate default memo Internal transfer: {source_account_number} → {destination_account_number} for XFER_INTERNAL when memo is blank
• Server-side fallback in Request.from_form via optional account_numbers; controller performs lightweight lookup for XFER_INTERNAL
• Client-side workstation autofill when both transfer accounts selected; preserves operator edits and regenerates only when memo was autofilled

Test plan

• bundle exec rails test test/services/transaction_entry/request_test.rb test/controllers/transactions_controller_test.rb passes
• Manual: open /transactions/new, select XFER_INTERNAL, pick source and destination -> memo autofills with Internal transfer: 1001 → 3001
• Manual: edit memo, change accounts -> manual value preserved
• Manual: blank memo, preview -> confirm -> posted memo matches generated default

Data / migration impact

• None

Financial logic risk

• None. Memo is traceability metadata; posting engine unchanged. Transfer policy already required one of memo or reference_number; reference defaults from Generate default manual transaction reference numbers #64 satisfy validation when memo absent.

UI notes

• Memo textarea autofills when transfer accounts are selected. Operator edits are preserved.

Made with Cursor