Feature Request: Enhanced Snapshot operator to work with Cycles for slot based A/B Rendering Comparisons

Blender's "Render Viewport Preview" could greatly benefit from supporting cycles. It respects render regions—but falls short by ignoring the camera's zoomed-in scale (which is great to use when shading), often resulting in mismatched captures that disrupt accurate side-by-side reviews.

To elevate this, Blender could better utilize its underutilized render slots system:

Enable a one-click "Snapshot" button in the viewport that captures the current rendered view (without overlays) and auto-stores it in the next available slot (e.g., Slot 01 for the first, Slot 02 for the next). After modifying shaders, lights, or other elements, the next snapshot would populate the subsequent slot. This would streamline A/B comparisons directly in the Image Editor, allowing users to toggle between slots for pixel-perfect diffs without manual file management or external tools.

This addition would boost productivity for shader artists, look-dev teams, and anyone iterating on renders, making Blender even more competitive in professional pipelines.