Add manifest for PWA

[B00M3000]

Is your feature request related to a problem? Please describe.
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I have an iPad and I would like to be able to install the dashboard as a PWA

Describe the solution you'd like
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Link a manifest. Offer what a PWA created off the site right now wouldn’t offer. Use “standalone” mode so the app is seemless.

Describe alternatives you've considered
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There exists sites save-as.app and WebClip but ultimately those are workarounds.

Additional context
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N/A

[0xJacky]

Added in f259877, you can now upgrade to dev version to test.