fix: add sessions empty state guidance

[GodHad]

Description

Adds clearer empty-state guidance to the Sessions page when no session data exists. The non-search/non-filter empty state now keeps the existing “No sessions found” heading and adds guidance telling users to run claude to start a session.

Search/filter empty states still show “No matching sessions” unchanged.

Closes #8

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• Tests pass locally (npm test)
• TypeScript build is clean (npx tsc --noEmit)
• No new console errors or warnings in the browser
• Responsive layout checked at multiple viewport sizes
• README updated if this PR adds or changes a user-facing feature

[ek33450505]

Thanks for the clean PR, @GodHad — really appreciate this being your first contribution to the repo. You hit the spec exactly: caught both empty-state render paths (table + virtualized), used the --text-primary theme token, and the DRY extraction into emptySessionCopy is the right call. Diff stayed surgical too — no scope creep, no formatting churn.

Approving and merging now. Hope you'll send more — the dashboard has a few more good first issue tagged tickets if you want another swing.

[GodHad]

Thank you for the thoughtful review and for merging it. I appreciate the clear issue write-up — it made it easy to keep the change focused.

I’ll keep an eye on the good first issue tickets and would be happy to take another swing where I can help. Glad to contribute.