fix(ui): minor platform ui tweaks (https://gitlab.com/postgres-ai/platform/-/issues/246)

Description

• Hide the buttons in the upper-right corner if the list is empty
• Swap the position and color of buttons
• Redirect users on /addorg route if the list is empty
• Hide getting started section if the there are no DBLab instances created
• Change delete button label inside the list

Related issue

https://gitlab.com/postgres-ai/platform/-/issues/246 https://gitlab.com/postgres-ai/platform/-/issues/249

Examples

Checklist

• MR description has been reviewed
• MR changes are functionally tested
• MR does NOT have API/CLI changes OR there are API/CLI changes and they have been reviewed & DOCS ARE ADJUSTED (reference doc, etc)
• MR does NOT have UI changes OR there are UI changes and they have been reviewed & UX IS REVIEWED