feat: normalize project directory names to kebab-case

[mwbrooks]

Changelog

The create command now makes project directory names normalized to kebab-case (lowercase, dash-delimited, no whitespace or special characters). For example, create "My App" now creates a my-app directory instead of My-App.

Summary

This pull request updates the create command to make project directory names that are normalized to kebab-case. For example, create "My App" now creates a my-app directory instead of My-App.

Updates getAppDirName in internal/pkg/create/create.go to convert app names to kebab-case:

• Converts to lowercase
• Replaces non-alphanumeric characters with dashes
• Collapses consecutive dashes into one
• Trims leading/trailing dashes
• Returns an error if the result is empty

Tests are rewritten as table-driven using the map pattern.

Requirements

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

[zimeg]

@mwbrooks LGTM! This is kind polish to find toward next steps:

$ slack create "Let's Get This Merged\!"

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.07%. Comparing base (ecfacb6) to head (67f69ff).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #374      +/-   ##
==========================================
+ Coverage   65.06%   65.07%   +0.01%     
==========================================
  Files         215      215              
  Lines       18179    18184       +5     
==========================================
+ Hits        11828    11834       +6     
+ Misses       5257     5254       -3     
- Partials     1094     1096       +2     

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[mwbrooks]

@zimeg Thanks for the quick review! 🙇🏻 I'm pleasantly surprised to see $ slack create "Let's Get This Merged\!" works alright!