paycheck-extension

This PR prepares the extension to be ready to Firefox add-on store. Also added manual install instructions in Changes needed for Firefox to allow add-on in store Firefox wants some in manifest. ID should be in format something@something Strict min version is exactly what means, 109 version was released January 2023, and Is the oldest Firefox version that supports Manifest V3 (Firefox will warn about using manifest v3 instead of v2 that can allow to older versions to use the add-on, but I don't really think it is worth the trouble) Publish Instructions Made these instructions for future reference and to help anyone that maybe wants to publish and extension. Not really needed, the Developer hub is very straight forward. 1. Go to Developer Hub, you require a Firefox account for this, 2. Click on “Submit your first add-on” (goes to this page) 3. Here we have to select a zip file to upload, we have two ways of doing this: 3.1 We can just grab everything we require (, and folder) and manually 'zipping' it 3.2 We can use web-ext provided by Mozilla to do this automaticity. Install with and use to make a zip of just the add-on requires 4. Upload the extension, if are any error or warning Firefox will let we know (most likely that Firefox will warning about using the Manifest V3 but is not a big deal) 5. In the next page we don't use anything to combine source code, minify or anything like that, so we click in no. 6. Next page will ask for add-on name, URL, contact info, description, and the license and if we want to do some notes for the reviewer. 7. Now the add-on will be going to be reviewed, and we can edit the product page in the Developer Hub

Added euro currency conversion from dollar and removed extra $ icon from the dollarAmount.

Some people want this extension to work in Firefox and to be published on the Add-ons marketplace. This issue will track progress of this feature, including if it's wontfix. I don't have any experience with making Firefox Add-ons (probably should work as-is since this is just a content script, might need another manifest), so if someone else wants to make the necessary changes that would be epic. https://twitter.com/TimRamboReal/status/1689408815186284545?s=20