feat(annotations): add logic for drawing/region annotation cursor input on rotated files

[kduncanhsu]

Summary

Adds support for live annotation drawing on rotated pages/images. This is in preparation for enabling annotation creation on rotated PDFs and images, where the annotation controls were previously hidden. Without this change, simply re-enabling annotation creation controls in the rotated state would cause the live drawing input to be offset from the user’s cursor.

This PR:

• Correctly maps window/browser mouse coordinates to annotation layer's local coordinate system, ensuring that live drawing/region input is correct when files are rotated
• Uses offsetWidth/offsetHeight (pre-transform dimensions) for percentage instead of getBoundingClientRect() which returns post-transform axis-aligned bounding box dimensions
• Removes the isRotated guard that blocked region annotation creation on rotated files

For further clarity, here is the live pointer capture flow when drawing annotations:

1. Mouse events provide clientX/clientY coordinates in screen space.
2. getPosition applies the inverse rotation transform to convert window/browser coordinates into the annotation layer’s local coordinate space.
3. getPoints/getShape normalize those local-space pixel coordinates into percentages using the annotation layer’s pre-transform (unrotated) offsetWidth/offsetHeight.

Test plan

• Rotate a PDF 90°, 180°, 270° counterclockwise and verify drawing annotations follow the cursor
• Rotate an image 90°, 180°, 270° and verify region annotations follow the cursor
• Verify annotations on unrotated (0°) files still work correctly
• Verify stored annotations remain anchored to content when rotation changes

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[ahorowitz123]

Can we have a comment explaining this whole algorithm? I'm finding it hard to follow even with the comments here

[kduncanhsu]

I tried incorporating clearer comments explaining the algorithm in the shared helper function within utils/rotate.ts. Let me know if it's easier to follow now, even with clear comments the logic can be quite confusing without diagrams so I could also walk through it in a watercooler session if that's helpful

[jmcbgaston]

Nice fix — the inverse-rotation approach is the correct way to handle CSS-rotated interaction layers, and using offsetWidth/offsetHeight for normalization is the right call. The math is duplicated almost verbatim between DrawingCreator and RegionCreator, and the rotated code path has no unit test coverage — worth addressing before merge. A few other smaller concerns inline.

Approve with minor changes.