Fix devcontainer: remove ruby feature redundant with jekyll base image

[Copilot]

The ghcr.io/devcontainers/features/ruby:2 feature fails to install because mcr.microsoft.com/devcontainers/jekyll already ships with Ruby and rbenv — adding the feature causes a conflict at build time (exit code 1).

Changes

• .devcontainer/devcontainer.json: Remove ghcr.io/devcontainers/features/ruby:2 feature. The postCreateCommand continues to run rbenv install --skip-existing using the rbenv already present in the base image, so .ruby-version remains the single source of truth for the Ruby version.

[fulldecent]

I loaded this branch in a devcontainer and ...

it did not crash, but.

ruby -v
ruby 3.4.9 (2026-03-11 revision 76cca827ab) +PRISM [x86_64-linux]

whereas the expected .ruby-version is

3.3.4

---

fix it so it actually uses the .ruby-version

---

i did a workaround with:

👋 Welcome to Codespaces! You are on a custom image defined in your devcontainer.json file.

🔍 To explore VS Code to its fullest, search using the Command Palette (Cmd/Ctrl + Shift + P)

📝 Edit away, then run your build command to see your code running in the browser.
@fulldecent ➜ /workspaces/github-pages-template (copilot/fix-devcontainer-issues) $ 

@fulldecent ➜ /workspaces/github-pages-template (copilot/fix-devcontainer-issues) $ 
@fulldecent ➜ /workspaces/github-pages-template (copilot/fix-devcontainer-issues) $ ruby -v
@fulldecent ➜ /workspaces/github-pages-template (copilot/fix-devcontainer-issues) $ rbenv
rbenv 1.3.2
Usage: rbenv <command> [<args>...]

Commands to manage available Ruby versions:
   versions    List installed Ruby versions
   install     Install a Ruby version using ruby-build
   uninstall   Uninstall a specific Ruby version
   rehash      Regenerate rbenv shims

Commands to view or change the current Ruby version:
   version     Show the current Ruby version and its origin
   local       Set or show the local application-specific Ruby version
   global      Set or show the global Ruby version
   shell       Set or show the shell-specific Ruby version

See `rbenv help <command>' for information on a specific command.
For full documentation, see: https://github.com/rbenv/rbenv#readme
@fulldecent ➜ /workspaces/github-pages-template (copilot/fix-devcontainer-issues) $ rbenv install
==> Downloading ruby-3.3.4.tar.gz...
-> curl -q -fL -o ruby-3.3.4.tar.gz https://cache.ruby-lang.org/pub/ruby/3.3/ruby-3.3.4.tar.gz
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 21.0M  100 21.0M    0     0  43.2M      0 --:--:-- --:--:-- --:--:-- 43.4M
==> Installing ruby-3.3.4...
-> ./configure "--prefix=$HOME/.rbenv/versions/3.3.4" --enable-shared --with-ext=openssl,psych,+


-> make -j 2
-> make install
==> Installed ruby-3.3.4 to /home/vscode/.rbenv/versions/3.3.4
@fulldecent ➜ /workspaces/github-pages-template (copilot/fix-devcontainer-issues) $
@fulldecent ➜ /workspaces/github-pages-template (copilot/fix-devcontainer-issues) $ 
@fulldecent ➜ /workspaces/github-pages-template (copilot/fix-devcontainer-issues) $ 
@fulldecent ➜ /workspaces/github-pages-template (copilot/fix-devcontainer-issues) $ ruby -v
ruby 3.4.9 (2026-03-11 revision 76cca827ab) +PRISM [x86_64-linux]
@fulldecent ➜ /workspaces/github-pages-template (copilot/fix-devcontainer-issues) $ eval "$(rbenv init -)"
@fulldecent ➜ /workspaces/github-pages-template (copilot/fix-devcontainer-issues) $ ruby -v
ruby 3.3.4 (2024-07-09 revision be1089c8ec) [x86_64-linux]
@fulldecent ➜ /workspaces/github-pages-template (copilot/fix-devcontainer-issues) $ ```

from inside the environment after it loaded.