Fixed
- Memory usage: Screenshot history now stores compressed PNG data instead of raw bitmaps, reducing memory from ~400 MB to ~30-50 MB with 10 entries. Floating thumbnail controller is also released after auto-dismiss instead of holding the full-res image until the next capture.
- Color picker cursor: Arrow cursor now shown over the color picker popup instead of crosshair.
- Color picker indicator: HSB gradient crosshair ring now tracks the actual mouse position accurately.
- Selection visibility: Fixed remaining case where the "Release to annotate" helper text disappeared at 1px selection dimensions.