[Feature] Group monitors into collapsible sections (like Uptime Kuma)

[akashmannil]

Summary

Add the ability to group monitors into logical sections on both the dashboard and status page.

Problem

With many monitors, it becomes difficult to organize and navigate them. Users want to visually group related monitors together (e.g., all VMs in one section, websites in another).

Proposed Solution

Implement monitor groupings similar to Uptime Kuma:

• Create named groups (e.g., "Docker Containers", "Websites", "External Services")
• Assign monitors to groups
• Display groups as collapsible sections
• Keep groupings separate from tags (they serve different purposes)
• Mockup Reference
• Uptime Kuma's implementation:

Uptime Kuma Grouping

[M1ck0]

This is the feature I am missing the most from Uptime Kuma