refactor: mutualize popup styles into shared SCSS file
Extract ~150 lines of identical CSS from ElementPopup and PagePopup into
a new _settings-popup.scss partial:
- Common popup structure (header, body, controls, CSS panel)
- Shared components (tooltips, toggle switches, inheritance button)
- CSS editor styling (readonly display, textarea)
Component-specific styles retained:
- ElementPopup: purple theme, button groups, checkboxes
- PagePopup: orange theme, margin grid layout
Reduces duplication and improves maintainability.
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Co-Authored-By: Claude <noreply@anthropic.com>
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