Add Ch Util, TX airtime and uptime to Device Info panel

[wittrup]

This PR surfaces additional DeviceMetrics fields in the Device Info panel:

• Channel Utilization
• TX Airtime
• Uptime

Telemetry from TELEMETRY_APP is merged into node.deviceMetrics so it aligns with existing battery/voltage handling.

Includes:

• i18n labels
• Improved uptime formatting (no zero-value segments)
• No breaking changes

[vercel]

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