improvement(ui): use shared geometry for standard icon actions
Document/image toolbars, microphone and public-chat actions, and playground buttons now use Button geometry props instead of repeating size, padding and corner classes. Existing event handlers, refs, ARIA state, recording animation and image-resize behavior are preserved.
- Desktop actions keep their 28px/32px targets; document toolbar and image-resize controls keep their 40px mobile targets.
- Toolbar and microphone actions use the existing quiet/active neutral treatments. Their hover fill is intentionally shared; formerly fixed 28px actions now scale to 35px with a 20px root font.
- The document toolbar focus treatment and image handle's bottom/right alignment remain explicit local exceptions.
Validation: all workspace type checks, import/API audits, lint and the complete EMCN suite passed; 76 relevant consumer tests passed. The diff design checker reports no new violations, and the full scan removes 19 styling findings with none added. Light/dark, hover, selected, disabled, keyboard focus, mobile and enlarged-text comparisons use actual components in local fixtures; dragging the actual TipTap image handle produces matching 240×120 images. No microphone recording or backend messaging was exercised. Before/after images are posted in a separate review comment.