Fix group case insensitive

[rbiamru]

Fixes #1699

What was happening

Group names were treated as case-sensitive on Linux. This allowed creating both default and defAult as separate groups, even though groups were intended to be case-insensitive.

What I changed

• Added validation to enforce lowercase-only group names in manager.go (Create, Get, Delete, Exists).
• Group names with uppercase characters are now rejected with a clear error.

Error: invalid group name: "MyGroup" (must be lowercase)

• Updated unit tests in group_test.go:
• Folded invalid-name tests into TestManager_Create (uppercase + mixed-case).
• Verified that duplicates with different casing are rejected at validation.
• Kept "success" and "already exists" cases intact.

How I tested

• Built and ran locally on Windows with Docker (nginx workload).
• Manual CLI tests:
  • ./thv group create MyGroup → error
  • ./thv run --group MyGroup docker.io/library/nginx:latest → error
  • ./thv group create mygroup → success

- Creating `defAult` since default.json already present in Local/toolhive/groups

• Unit tests pass:

[blkt]

Hi @rbiamru thank you for your contribution. I left a small comment about the resulting UX, let's see what other folks think.

[blkt]

issue: I don't think this is the right way of fixing this problem.

The way this is implemented, the user would think that he/she was able to create a group named MyGroup with a mix of uppercase and lowercase letters, while that's not the case. Since this is a user defined property and the user will refer to it from the CLI, it might be better to ensure that name == strings.ToLower(name) and return a specific error when that's not the case.

Note that this would apply to all routines, not just Create.

@amirejaz what do you think about it?

[amirejaz]

I agree @blkt , enforcing lowercase with a clear error across all routines makes sense.

[rbiamru]

Thanks for the feedback! I updated the implementation to enforce lowercase validation (no normalization) and updated tests to assert errors for uppercase & mixed-case names. Verified group create / run --group. Both CLI and unit tests now pass.

/cc @blkt @amirejaz

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 33.43%. Comparing base (0b47fde) to head (2e35eb6).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1711      +/-   ##
==========================================
+ Coverage   33.42%   33.43%   +0.01%     
==========================================
  Files         216      216              
  Lines       26716    26721       +5     
==========================================
+ Hits         8929     8934       +5     
  Misses      17138    17138              
  Partials      649      649              

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[coveralls]

coverage: 35.744% (+0.01%) from 35.733%
when pulling 2e35eb6 on rbiamru:fix-group-case-insensitive
into 0b47fde on stacklok:main.