Implement monitoring dashboard into Cloud EM

[AlinaBelousovaUX]

Add a dedicated Monitoring tab to the database diagnostics page and update related navigation elements to improve monitoring accessibility.

Database Diagnostics Page

Add "Monitoring" tab as second tab position (after Info). Display "New" label (disappears after 14 days). Use segmented control component for tab navigation inside dashboard.
Content: Embed existing YDB console monitoring dashboard.

Navigation Updates

• Add "Monitoring" option to database context menu in navigation tree.
• Change global header button from "Monitoring" to "Monium". Add tooltip to "Monium" button: "Full monitoring in Monium".

<img width="904" height="476" alt="Image" src="https://github.com/user-attachments/assets/ad7a2766-b557-41a0-a298-b2c63d624f38" /Новая

Figma dark theme
Figma light theme

UX ticket: feat: design for cloud monitoring #2965