Create gh-pages (a website) where you can try out the extension without installing it

[WofWca]

This is also helpful for people who are afraid (or other reasons) to install the extension (see #57).

Also need to consider making it an installable PWA, to play local (or non-local?) files.

Maybe also need to add a way to open non-local files in the local-file-player, with a link to the video file.

The biggest obstacle here is the usage of Web Extension API (e.g. browser.tabs.query(...).

Maybe we can add some ifs like (if (BUILD_DEFINITIONS.STANDALONE_DEMO_PAGE), so that Web Extension API is never used when the condition is true. So basically search for all the occurrences of browser..

I think we could utilize local-file-player and put popup in an <iframe>.

For popup, this may also help: https://github.com/WofWca/jumpcutter/compare/popup-separate-tab

[WofWca]

The simplest approach would be just to fork and make a barely working prototype at first.