Nav Aids: 'lastViewedSvg' conflicts if measurable categories have different number of nav aids

[rovats]

Eg: Measurable Category A has two SVG diagrams Measurable Category B has one SVG diagrams

Navigate to Category A and switch to second SVG diagram, ls.lastViewedSvg.main.measurable-category.list will be set to: {group: <some_group>, index: 1}

Then, Navigate to Category B, the first (and only) SVG diagram won't be selected, because the last stored index in ls.lastViewedSvg.main.measurable-category.list is 1, and there is no diagram at index 1 in Category B

[davidwatkins73]

Need to pass is some kind of qualifier to the svg-diagrams widget so the local storage key is unique for page/category.

• bonus points: port to svelte :)