Have `gleam remove` validate package names.

Thank you for wonderful language, I am enjoying it a lot.

I have installed a package to my project, played with it a little bit and as I found out that I do not need it I wanted to remove it. Somehow naturally I have searched history for the installation command and just changed the subcommand install to remove. To my surprise it told me that the package is not a dependency. Soon I have realized that I need to specify the package without the version constraint.

I believe the CLI should accept the package@version variant and just remove the package (if I understand it correctly that we cannot have 2 versions of the same package installed at the same time).

Alternatively the CLI should explicitly reject the @version variant and inform the user that they need to specify the package without the version.

Failing silently seems misleading and can cause confusion.

➜  gleavent git:(main) ✗ gleam remove gleam_otp@1
error: Package not found

These packages are not dependencies of your package so they could not
be removed.

  - gleam_otp@1


➜  gleavent git:(main) ✗ gleam remove gleam_otp  
    Removed gleam_otp

My env:

MacOS 26.6.2
gleam 1.18.1