Fix link rendering in download dialogues

[jamesmisson]

This tightens up the rendering of links in the download dialogue for both the PDF and OSD extensions.

PDF Download Dialogue

The link was being built with string concatenation. I've replaced this with attributes supplied to the JQuery element via an object.

This manifest has a rendering ID with Javascript that is now avoided: https://gist.githubusercontent.com/jamesmisson/15c81934ef12175441cab96ac53d0653/raw/3d67b52f1b92a2a0f7f9ffadd6648ee4d215c023/pdf-download-rendering.json

OSD Download Dialogue

The Rendering component allowed Javascript to be supplied in the rendering ID. I've added a filter that checks that the ID begins with http/https, and used it in the relevant places. We should probably give some thought to what passes through this filter, but this implements the mechanism at least.

Download Option section headings are rendered conditionally via has*Renderings functions (e.g. hasCanvasRenderings, so I've used the new getSafeRenderings in all of these, as well as in the Renderings themselves.

This fix works with the manifest supplied: https://gist.githubusercontent.com/jamesmisson/1086007969f7f9947a729caf06b139d8/raw/e548676547355a248f85a912e6584fb7834b2281/poc3.json

[vercel]

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Project	Deployment	Actions	Updated (UTC)
universalviewer	Ready	Preview, Comment	Jul 16, 2026 7:59pm
universalviewer.dev	Ready	Preview, Comment	Jul 16, 2026 7:59pm

[vercel]

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[demiankatz]

Thanks, @jamesmisson -- this looks good to me.

One thing, though: this PR is targeted against dev; if we want to issue another 4.4.x bug fix release, it should be rebased onto the release-4.4 branch instead (or we can merge it as-is and cherry-pick the fix back to the release branch).

I'm still conferencing for the rest of the week, so my time is limited -- but let me know if you need help with anything and I'll do my best to help when I'm able!

[demiankatz]

Looks good to me now; thanks, @jamesmisson!