Release v1.1.0

feat: color picker, status palette colors and style polish (v1.1.0)

- ModernColorPicker: themed modal picker (saturation/value field, hue and
  optional alpha bars, hex + RGB input, presets, old/new preview), built
  conflict-free like ModernMessageBox - no custom controls, no DP registrations
- ThemePalette: optional Success/Warning status colors (Brush.*/Color.*),
  followed by toasts (which now inherit the owner palette), the warning
  dialog icon and the new BadgeSuccess/BadgeWarning styles
- IconButton carries the icon font at 16px - bare glyph content works
- PlaceholderBox: placeholder-via-Tag text box without the magnifier
- ToggleSwitch retargeted to ToggleButton (fits CheckBox and ToggleButton)
- Tighter 6px text indent on TextBox/ComboBox (no icon-sized left margin)
- Expander body respects Padding; TreeView child indent is the overridable
  Margin.TreeIndent token (per tree or window-wide)
- Gallery pages, docs sections and regenerated screenshots for all of the
  above (plus a refresh of doc images that had gone stale on master)