fix(zoom): bug fixes for pinch to zoom images

[kduncanhsu]

Summary

This PR includes two bug fixes for pinch to zoom functionality for images:

• Fix pinch-to-zoom out with rotated images: initialRect and initialWidth (used for zoom-out edge clamping) were captured at load time and never updated on rotation. After rotating, the clamping would guide the image toward a stale pre-rotation position, causing it to jump when snapping back to center. Added recalculateInitialRect() which temporarily sizes the image to its fit-to-viewport dimensions for the current rotation, captures the correct initialRect/initialWidth, then restores the actual dimensions without visual flicker.
• Allow pinch-to-zoom out past fit-to-viewport size: Previously, pinch zoom was clamped at initialWidth (the fit-to-viewport size). Removed that floor so users can continue zooming out. When below initialWidth, uses simple center-based zoom via adjustImageZoomPadding() (matching toolbar zoom-out behavior) instead of cursor-anchored positioning with edge clamping.

Test plan

• Pinch to zoom in on an unrotated image, then pinch to zoom out — image should smoothly return to center
• Rotate an image, then pinch to zoom out — image should smoothly return to center (no jumping)
• Zoom in, rotate, then pinch to zoom out — image should smoothly return to center (no jumping)
• Pinch to zoom out past the fit-to-viewport size — image should shrink centered in the viewport
• Verify toolbar zoom in/out buttons still work correctly
• Verify pinch-to-zoom in still anchors to cursor position correctly

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