Classify dividend payments by distribution type (capital gain, return of capital, etc.)

Let investors classify each cash distribution as an ordinary dividend, a capital gain distribution, a return of capital, or interest. A single special payment should be editable without changing the general dividend tax rule for every payment from that holding. Show the chosen type in the dividend log, reports and exports. Ordinary payments should remain in dividend income, capital gain distributions should be reported separately, and returns of capital should adjust the holding's cost basis where the selected tax treatment supports it. Keep past payments unchanged until the investor reviews them, and make it clear when a distribution has not been classified beyond the ordinary default.