Expand NiceGUI dashboard structure

[BytecodeBrewer]

Goal

Expand the NiceGUI dashboard structure after the first working prototype.

Why

The first NiceGUI dashboard should prove that ARGUS can display real data and metrics. After that, the interface needs a cleaner structure for navigation, layout and future analytics modules.

Scope

• Improve dashboard layout
• Add basic navigation or page sections
• Separate UI components where useful
• Improve chart and metric card presentation
• Add loading/error states for data requests
• Prepare structure for future storage and reporting features

Acceptance criteria

• Dashboard layout is clearer and easier to extend
• Metrics are displayed in readable UI components
• Data loading and error states are handled
• NiceGUI code is structured into maintainable components where useful
• UI remains separated from data-source and metric logic
• Existing tests still pass

Note

Priority: Should