feat(cmd): add --name flag to disambiguate 'agent' shortcut

[srtaalej]

Summary

The create agent command is a shortcut to AI Agent templates, but users who want to name their app agent had no clear way to do so. Add --name flag to explicitly set the app name, bypassing the shortcut behavior.

Follow up to PR #326

Behavior

Command	Result
create my-app	App named "my-app"
create agent	AI Agent shortcut
create agent my-app	AI Agent, named "my-app"
create --name agent	App named "agent" (NOT an AI Agent)
create agent --name foo	AI Agent, named "foo"

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.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 64.69%. Comparing base (890a67e) to head (6648deb).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #327      +/-   ##
==========================================
+ Coverage   64.68%   64.69%   +0.01%     
==========================================
  Files         212      212              
  Lines       17771    17778       +7     
==========================================
+ Hits        11495    11502       +7     
  Misses       5203     5203              
  Partials     1073     1073              

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[mwbrooks]

✅ Wow, I never imagined we'd turn around and land --name so quickly! Thank you 🙇🏻

🧪 Local testing works great!

📝 I've left a few minor suggestions around the help information. The goal is to add clarity. I also left a suggestion around 2 additional test cases so that future changes don't break the expected functionality.

[mwbrooks]

praise: Love the comment calling out that --name flag overrides any position app name argument.

[mwbrooks]

suggestion: Since our intent is for --name flag to override the <name> argument, perhaps we should have test for the combination to guarantee that future code changes don't create a regression in this behaviour:.

It may also be a good idea to test the agent use-case.

The test cases could be:

1. slack create my-project --name my-name → Expects my-name
2. slack create agent my-project --name my-name → Expects my-name