Task: Sync Qt codegen for currency

Ensure the Qt codegen profile produces output matching the repository for currency (client model, MDI window, detail dialog, history dialog, controller, UI files). Record every delta with category and decision.

• Qt profile produces zero diff or every delta is classified and the decision recorded; fix commits present where required; build passes.

(Implementation strategy. Written when work starts; key decisions are distilled into the parent story's * Decisions at close, but the plan itself stays — it is the historical record of what we did.)