T-b260588

Changes:

• UI editor: control palette expanded from 3 to 9 - label, panel, image, slider, progress bar, dropdown
• UI editor: horizontal/vertical text alignment for all controls
• UI editor: per-type properties (sprite, options, value/min/max, fill color)
• New blocks: value of control, state of toggle; set-control-property dropdown grew from 14 to 21 options
• Style: monochrome defaults (black/white) for regular controls; light gray background + green fill for slider/progress/dropdown/panel
• Custom slider rendering in generated mods (green fill, black thumb, mouse drag)