Improve menu bar status display stability

[HerbertGao]

Summary

• render the complete menu bar label as one image so MenuBarExtra preserves custom layouts and fixed sizing
• use fixed-width monospaced readings, with white values and thermal coloring limited to the fan icon
• add a persisted horizontal/vertical layout preference
• keep the vertical layout compact by omitting the degree symbol
• preserve accessible temperature and RPM descriptions, with a visible fallback if rendering fails

Behavior

• Horizontal: icon and reading side by side; temperature keeps the degree symbol
• Vertical: compact stacked icon and reading; temperature omits the degree symbol
• Icon only: unchanged