fix: brev ls spinner hanging during onboarding quick tour

[hakhandelwal11]

After first login, the quick tour asks the user to run brev ls, which starts a spinner waiting for brev shell in another terminal. However, the spinner never stops because it checks HasRunBrevOpen instead of HasRunBrevShell, so the completion condition is never met.

Fix: Updated the condition in doBrevShellOnboarding. The polling loop now uses shellOnboardingPollDone(res), which considers onboarding complete when the onboarding state is non-nil and HasRunBrevShell is true. This ensures the spinner correctly detects completion and exits cleanly.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 17.69%. Comparing base (88dc335) to head (dd8a7a1).
⚠️ Report is 27 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/cmd/hello/steps.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #348      +/-   ##
==========================================
+ Coverage   14.77%   17.69%   +2.91%     
==========================================
  Files         127      140      +13     
  Lines       16977    18483    +1506     
==========================================
+ Hits         2508     3270     +762     
- Misses      14182    14853     +671     
- Partials      287      360      +73     

Flag	Coverage Δ
Linux	17.69% <0.00%> (+2.91%)	⬆️

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