Upgrade to Manifest V3

[timdorr]

https://developer.chrome.com/docs/extensions/mv3/intro/mv3-migration/

While there are a lot of controversies around the new manifest format, I don't believe most affect us. The advantages are getting ahead of enforcement later (we've got a year until V2 extensions stop working) and getting into a faster approval workflow for updates on the Web Store.

Probably the most consequential is the move from background pages to service workers. Since we maintain a store on the background page, that logic will need to be persisted. We can probably get fancy and wrap some of the ways we access that store to lazy load it from storage (window.store -> getStore()). Here are the docs on migrating to SWs: https://developer.chrome.com/docs/extensions/mv3/migrating_to_service_workers/

I don't think there's much else that affects us. Some minor things around actions changes, but that's mostly just moving stuff around in the manifest.json.

Edit: Pinning this since it's got a deadline associated with it. We'll have to take this seriously.

[respectYourNeighbour]

I also get some warning regarding this:

• Permission 'notifications' is unknown or URL pattern is malformed.
• Permission 'contextMenus' is unknown or URL pattern is malformed.

[Methuselah96]

https://developer.chrome.com/blog/resuming-the-transition-to-mv3/