Enhanced temperature DataValue rendering

[luke-kearney]

Description

Enhance the existing extruder.temperature and heater_bed.temperature DataValue renderers.

Tasks

• Add icon/sprite support alongside temp readout (e.g. nozzle icon + "210°C")
• Support target vs actual display (e.g. "210°C / 220°C")
• Verify with mock mode

Notes

Renderer already supports these keys (from Tangent 2A). This is visual polish.

Files

• firmare: src/display/Renderer.cpp

Labels

area:firmware, type:enhancement