feat: fix install script mime type

[mchristopher]

Adding a Cloudflare Worker which will re-write the Content-Type HTTP header with the correct MIME type for a shell script.

This is needed since GitHub pages doesn't support overriding the MIME type of a file, and the only "index" file that is supported must end in .html (which automatically gets the type text/html).

[github-actions]

LCOV of commit daf70ed during CI #2153

Summary coverage rate:
  lines......: 85.6% (2423 of 2832 lines)
  functions..: 54.0% (334 of 619 functions)
  branches...: 63.0% (290 of 460 branches)

Files changed coverage rate: n/a

[sdankel]

Looks good, thanks!