Add Torque lens CSS

This MR splits the lens-related styling off from torque!102 (merged) and puts it here, in LFCTheme, where it belongs.

Note that it uses a CSS file, not a LESS file, and so it uses the @import (inline) directive. In future, when we move entirely away from LESS, we would replace importing into skin.less with just listing all the CSS files in the skin.json's styles array -- but that should wait until that specific task.

Affects but does not resolve ots/llm/meta#49