Enhanced progress bar DataValue rendering

[luke-kearney]

Description

Enhance the existing print_stats.progress DataValue renderer with visual improvements.

Tasks

• Custom bar height and border/outline
• Color based on progress percentage (e.g. gradient)
• Support label prefix (e.g. "Progress: ████████░░ 73%")
• Verify with mock mode

Notes

Renderer already supports DataValue key print_stats.progress (from Tangent 2A). This is visual polish.

Files

• firmare: src/display/Renderer.cpp
• firmare: src/engine/Config.h (add progress bar style fields if needed)

Labels

area:firmware, type:enhancement