Can't preview markdown file in Penny as they get `text/turle` type instead of `text/plain`

Search terms you've used

contentType, markdown

Bug description

On the community solid server recipe using Penny UI , text file uploaded as .md .markdown or CSS's by default README.$markdown can't get priviewed by penny.
In the debugger I can see they have the text/turtle content type, instead of text/plain ( which I believe is the correct type).

To Reproduce

1. clone and run CSS penny recipe
2. Create a new account and a pod
3. Login
4. on a shell echo bar > foo.md
5. upload foo.md to your pod using penny
6. on penny, open foo.md

Expected result

Penny should preview the file ( "bar" ) as if it was a plain text file
( check the result if you use foo.txt instead of foo.md in step 4 )

Actual result

Penny shows This resource is empty.

Environment

System:
OS: Linux 5.15 Fedora Linux 36 (Thirty Six)
CPU: (4) x64 Intel(R) Core(TM) i5-8350U CPU @ 1.70GHz
Memory: 4.72 GB / 11.39 GB
Container: Yes
Shell: 5.9 - /home/user/.nix-profile/bin/zsh
Binaries:
Node: 18.16.1 - ~/.nvm/versions/node/v18.16.1/bin/node
npm: 9.5.1 - ~/.nvm/versions/node/v18.16.1/bin/npm
pnpm: 8.11.0 - ~/.nvm/versions/node/v18.16.1/bin/pnpm
bun: 1.0.15 - ~/.bun/bin/bun
Browsers:
Chrome: 121.0.6167.184
Chromium: 111.0.5563.64
npmGlobalPackages:
corepack: 0.17.0
create-preact-app: 0.2.0
date-prompt: 1.0.0
eas-cli: 7.1.2
expo-cli: 6.3.10
npm: 9.5.1
pnpm: 8.11.0

Additional information

Start with the linked Community Solid Server Penny recipe and reproduce the upload and preview flow using foo.md and foo.txt. Compare the content types observed in the debugger, then trace the Penny preview entry point to determine why Markdown is treated as text/turtle. Done means uploaded .md and .markdown files preview their plain text content like foo.txt.