v0.26.0 — Bad-debt relief, mixed-activity deduction and cash-basis VAT

Three VAT mechanisms that used to mean a spreadsheet and a calendar reminder now run inside Biurko.

• Bad-debt relief, watched for you. Every invoice that goes 90 days past its due date is picked up automatically. On the sales side you get a proposal — reclaiming the VAT is your right, and only you know whether the conditions are met — with the correction already worked out per rate. On the purchase side the correction is prepared as confirmed, because giving that input VAT back is a statutory duty, not a choice. When the debt is settled after all, the give-back is prepared for the period the money arrived — proportionally, if it arrived in instalments.
• Mixed activity, deducted proportionally. If you sell both taxable and exempt services, mark a purchase as mixed and Biurko deducts its input VAT by your annual proportion (and prewspółczynnik, if you use one). Biurko computes what your own registers suggest for the year — the coefficient you actually apply stays your decision. The year-end correction lands in the first period of the following year as an internal document.
• Cash-basis VAT. Small taxpayers settling on the cash basis can switch the recognition method in the tax settings: an invoice then enters the register in the period the money moved, for exactly the share that moved. Instalments split across periods and always add back up to the whole invoice, to the grosz.

Everything lands in JPK_V7 where it belongs — the corrections in K_46/K_47 and P_68/P_69, the proportion correction in K_44/K_45 — and every generated file is checked against the official schema before you see it.