Initial prototype of the V3 manifest extension (#4357)

* Initial prototype of the V3 manifest extension

* Make sure the content script is only injected once

* Implement addNote button

* More separation work for tasks, implement archive and update note

* Add back missing functionality, add guide to install Extensions

* Revert v2 changes

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Co-authored-by: Thomas Rogers <Podginator@gmail.com>

pkg/extension/src/manifest.json

@@ -95,4 +95,4 @@
   "web_accessible_resources": [
     "views/toast.html"
   ]
-}
+}