feat(auth): auto-prompt login when no workspaces connected

[srtaalej]

Changelog

We now prompt a login if no authentications are available when running a command that requires credentials instead of exiting with an error.

Summary

When running commands like slack run without any authenticated workspaces, automatically prompt the user to sign in instead of showing an error.

Manually test by clearing credentials (slack logout --all) and running slack run

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

❌ Patch coverage is 90.90909% with 1 line in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (main@784de53). Learn more about missing BASE report.
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/prompts/app_select.go	90.90%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #331   +/-   ##
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  Coverage        ?   64.67%           
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  Files           ?      212           
  Lines           ?    17782           
  Branches        ?        0           
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  Hits            ?    11501           
  Misses          ?     5206           
  Partials        ?     1075           

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[srtaalej]

Dear kind reviewers,
changes to @app_select.go are working as expected. I've tested with the following commands

  ./bin/slack deploy
  ./bin/slack activity
  ./bin/slack trigger list
  ./bin/slack env list
  ./bin/slack datastore query

🫡

[mwbrooks]

✅ Works beautifully @srtaalej and very elegant implementation! 💅🏻

🧪 Testing locally works well on both slack run and slack manifest validate. Also confirmed commands like slack create and slack auth list do not prompt to login.

✏️ I've left 1 suggestion but that would be nice to add, but non-blocking.