Only one file contains the string “<form” (case-insensitive) and the one file which does contain this isn’t an HTML file (and doesn’t have the form).
This requirement of a pure HTML version of the form at deploy time is documented here:
While the two articles are fairly framework-specific, the code demonstrates how to prerender forms when working with them in a web application.
To summarize, there is no HTML form parsed during the deploy. It does appear there has been at one point because I do see a form handler prepared to receive the form. However, the deploy above doesn’t appear to have one.
You might try creating the HTML version of the form, including it with the deploy, and see if that works.