[6.x] Image cropping

[jackmcdade]

Uses cropper.js to add a new image crop feature, complete with aspect ratio and orientation flipping.

When finished cropping you can choose to save as a new image or replace the existing one.

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Note

Medium Risk
Adds a new client-side image cropping and re-upload flow, including optional overwrite of existing assets, which could impact asset integrity and upload behavior if edge cases slip through. Changes also adjust stack open timing (Stack.vue) which may affect other stack consumers’ lifecycle assumptions.

Overview
Adds an image cropping feature to the asset editor using cropperjs, including a new CropEditor.vue stack with aspect-ratio presets, orientation flipping, keyboard shortcuts, and basic CORS/error handling.

Introduces a post-crop confirmation flow to either save a new copy (timestamped upload) or replace the original (overwrite upload), then redirects to the new asset or reloads the current one and busts image caches. Also tweaks Stack.vue to emit opened on the next tick and adds a new crop toolbar icon.

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