Add configurable rotation support to landscape view

[cornhundred]

Summary

• add a rotate trait to the Landscape widget API and forward it through the front-end renderer
• introduce shared rotation utilities and apply the rotation matrix to all deck.gl landscape layers
• update viewport calculations to fetch tiles and filter data correctly when the visualization is rotated

Testing

• pytest --override-ini addopts="" tests/unit/test_viz/test_widget.py

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Codex Task

[Copilot]

Pull Request Overview

This PR adds configurable rotation support to landscape visualizations by introducing a rotate parameter that allows users to specify rotation angles in degrees for 2D views.

Key Changes:

• Added rotate trait to the Landscape widget API (Python and JavaScript)
• Implemented shared rotation utilities with matrix transformations and point rotation functions
• Updated viewport calculations to correctly handle rotated visualizations when fetching tiles and filtering data

Reviewed Changes

Copilot reviewed 13 out of 14 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/celldega/viz/widget.py	Added rotate traitlet to expose rotation angle parameter
js/widget.js	Forwarded rotate parameter from model to renderer
js/viz/landscape_ist.js	Initialized rotation state with center coordinates and passed to trx_layer
js/utils/rotation.js	Created rotation utilities including matrix building and point transformation functions
js/deck-gl/layers/trx_layer.js	Applied rotation matrix to transcript layer
js/deck-gl/layers/simple_image_layer.js	Applied rotation matrix to simple image layer
js/deck-gl/layers/path_layer.js	Applied rotation matrix to path layer
js/deck-gl/layers/nbhd_layer.js	Applied rotation matrix to neighborhood layer
js/deck-gl/layers/image_layers.js	Applied rotation matrix to image layers
js/deck-gl/layers/edit_layer.js	Applied rotation matrix to edit layer
js/deck-gl/layers/cell_layer.js	Applied rotation matrix to both PointCloudLayer and ScatterplotLayer variants
js/deck-gl/layers/background_layer.js	Applied rotation matrix to background layer
js/deck-gl/core/calc_viewport.js	Updated viewport bounds calculation to account for rotation and modified transcript/cell filtering logic

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[cornhundred]

I used Codex to implement a rotation argument for the Landscape widget. It works in my testing and the implementation looks ok. I'm gong to use it to rotate a Xenium dataset to match the orientation with a Visium HD dataset.