When editing text inside a group element, the text cursor was appearing
in the wrong position because only the text element's own transform was
being considered, ignoring transforms from parent groups.
This change:
- Adds a new #getAccumulatedMatrix() method that traverses up the DOM tree
from the text element to the SVG content element, collecting and multiplying
all transform matrices along the way
- Updates the init() method to use this accumulated matrix instead of just
the text element's transform
- Updates test mock to include getSvgContent() method
Fixes the issue where editing text inside a transformed group would show
the cursor at the wrong position.
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
