mix livepanels.check (livepanels v0.1.0)

Validates LivePanels canvas on_mount declarations in the current Mix app.

mix livepanels.check

The task compiles the application, finds LiveViews that use LivePanels.Canvas, and runs the same runtime config builder the canvas uses during mount. This gives projects an explicit check for malformed runtime options without moving that work back into macro expansion.