[editor] Refactor and polish Image + Text edit panels

- ImageEditPanel (62KB) extract into sub-components

- TextEditPanel (70KB) extract into sub-components

- Consistent UX: crop/resize, caption editing, alt text, formatting toolbar

- Style preset picker more prominent in text panel

- Cross-project section copy (user feedback)

- Image opacity control (user feedback)

**Files:** `src/components/editor/ImageEditPanel.tsx`, `src/components/editor/TextEditPanel.tsx`