[UX]: add a clearer first-run onboarding section to the dashboard

[MatrixAdventurer]

Summary

After entering the dashboard, the next steps are not obvious enough for first-time users.

During onboarding, the critical path is usually:

1. understand where to start
2. get API URL
3. create/copy API key
4. connect a tool
5. verify memory works

Right now, this path feels too implicit.

Suggested improvement

Add a clear first-run Get started / onboarding section on the dashboard home page.

Suggested steps:

• Copy API URL
• Create API key
• Connect your tool
• Test memory
• Try Git for Memory

Why this matters

• Reduces first-run confusion
• Shortens time-to-first-success
• Makes the dashboard feel action-oriented instead of exploratory-only

Expected behavior

A new user should be able to enter the dashboard and understand the next 3-5 steps within seconds, without hunting across multiple pages.

[MatrixAdventurer]

Linked to umbrella onboarding issue #123. Keeping this open as a concrete dashboard-first-run task.

[MatrixAdventurer]

Relationship note: treating this as a concrete child slice under #123 rather than a duplicate. #123 is the broader onboarding-flow umbrella; this issue is specifically the dashboard first-run / "what do I do next?" surface.