Improve area navigation and add integrated copy support

[danielsgeller-cloud]

Using pgrsql, switching between the database area, query area, and result area feels awkward and slows workflow. Additionally copying text such as error messages from the UI is not straightforward, which makes debugging and issue tracing difficult.

Proposed Improvements:

1. Navigation Enhancements
   Explore better ways to switch focus between the database list, the query editor, and the result pane. Possible approaches include improved Tab cycling with clear focus indication, shortcut keys to jump directly to each area, and optional mouse support for area selection.

2. Integrated Copy Support
   Enable intuitive text selection and copying directly from the interface with cursor highlighting, standard copy shortcut (Ctrl+C), and a brief "Copied" notification in the top right.

Rationale:
I recently received an error message while working in pgrsql and was unable to easily copy it for debugging and sharing with other tools. Better navigation and integrated copy support will improve usability and speed up troubleshooting.