The trophy classes were using static() to specify the images for the

various DPIs for each trophy. This ended up causing static lookup state

to be initialized too early, breaking extension packaging.
To fix this, we now use the new static_lazy() found in Djblets, which

will let us reference the static media we want, but actually perform the

lookups on demand at runtime.

Tested building an extension with static media. It built successfully.