*Edit, I found this section, and will update my answer when I've successfully deployed to production.
https://learn.microsoft.com/en-us/office/dev/add-ins/publish/publish?view=excel-js-preview
Deployment documentation is hard to find. The dist folder contains the files for a Production environment. Look for the Resources node in your manifest.xml. Here is one referring to files in localhost. These are in the dist folder. You'll want to upload the contents of the dist folder to a server file share, or S3 bucket, after all of your changes have been built.
<Resources>
<bt:Images>
<bt:Image id="Icon.16x16" DefaultValue="https://localhost:3000/assets/icon-16.png"/>
<bt:Image id="Icon.32x32" DefaultValue="https://localhost:3000/assets/icon-32.png"/>
<bt:Image id="Icon.80x80" DefaultValue="https://localhost:3000/assets/icon-80.png"/>
</bt:Images>
<bt:Urls>
<bt:Url id="Functions.Script.Url" DefaultValue="https://localhost:3000/public/functions.js"/>
<bt:Url id="Functions.Metadata.Url" DefaultValue="https://localhost:3000/public/functions.json"/>
<bt:Url id="GetStarted.LearnMoreUrl" DefaultValue="https://go.microsoft.com/fwlink/?LinkId=276812"/>
<bt:Url id="Taskpane.Url" DefaultValue="https://localhost:3000/taskpane.html"/>
</bt:Urls>
<bt:ShortStrings>
<bt:String id="Functions.Namespace" DefaultValue="FinTools_Azure"/>
<bt:String id="GetStarted.Title" DefaultValue="Quantitative Finance SaaS"/>
<bt:String id="CommandsGroup.Label" DefaultValue="Commands Group"/>
<bt:String id="TaskpaneButton.Label" DefaultValue="Show Taskpane"/>
</bt:ShortStrings>
<bt:LongStrings>
<bt:String id="GetStarted.Description" DefaultValue="FinTools_Azure has successfully loaded"/>
<bt:String id="TaskpaneButton.Tooltip" DefaultValue="Click to Show a Taskpane"/>
</bt:LongStrings>
</Resources>
Then update all of those links, and anywhere else in manifest.xml that refers to localhost