* fix(dashboard): make MoA presets modal opaque and readable
Card defaults to bg-background-base/80 glass, so the Mixture of Agents
dialog let the Models page bleed through — especially on Cyberpunk/mobile.
Portal an opaque dialog shell above the z-2 dashboard column, and ignore
Escape while the nested model picker is open.
* test(web): lock dashboard modal shell to opaque panel classes
Guard the MoA/dialog shell contract so glass Card defaults cannot
quietly return to modal panels, and Escape stays picker-aware.
