Description

Resolve #6542
Resolve #6661

Problem:
After restoring tour auto-start in #6565, opening a new browser tab triggers the tour again. It should only auto-start once per browser profile/session.

Root cause:
FIRST_VISIT_KEY was stored in sessionStorage, which is scoped per tab. Each new tab appeared as a "first visit."

Change:
Switch FIRST_VISIT_KEY from sessionStorage to localStorage to share state across tabs.

Behavior:

• Tour auto-starts only once across all tabs for the same browser profile.
• Manual start via the help button still works.
• Completion is still tracked via TOUR_COMPLETED_KEY in localStorage.

Files Changed

sky/dashboard/src/hooks/useFirstVisit.js

• Read/write/remove FIRST_VISIT_KEY from localStorage instead of sessionStorage.
• Updated inline comment to reflect cross-tab behavior.

Testing

1. Open the dashboard in one tab: tour auto-starts once.
2. Open a second tab (same profile): tour does not auto-start.
3. Click "Dismiss" on the prompt: no further prompts.
4. Manually start tour via help button: works.
5. After completion, refresh and open new tabs: tour does not reappear.

Tested (run the relevant ones):

• Code formatting: install pre-commit (auto-check on commit) or bash format.sh
• Any manual or new tests for this PR (please specify below)
• All smoke tests: /smoke-test (CI) or pytest tests/test_smoke.py (local)
• Relevant individual tests: /smoke-test -k test_name (CI) or pytest tests/test_smoke.py::test_name (local)
• Backward compatibility: /quicktest-core (CI) or pytest tests/smoke_tests/test_backward_compat.py (local)