Layout templates (onboard and stop contexts)

[fabianabarca]

Description

Provide base layouts and templating hooks.

Acceptance Criteria

• Onboard and stop layouts implemented
• Theming and content regions defined
• Sample data to preview

[fabianabarca]

Tracked in #1

[gonguma]

Starts: 2025-10-01
Ends: 2025-10-10
Depends on: #2. The device and group models must be defined before creating the layout templates for the onboard and stop contexts.