default ladder texture cuts VIS

Currently the default hl2 texture tools/toolsinvisibleladder cuts VIS and thus increases compile time among other issues.

Also, Valve forgot to use the alpha channel which apparently exists and allows the texture to become transparent in hammer.

My recommendation is editing/overriding the default or providing a fixed .vmt

I have a fix version here if you would like to use it:
https://github.com/meatspace/vizzys_tool_textures/blob/main/materials/tools/toolsinvisibleladder_fix.vmt

Inspect the default tools/toolsinvisibleladder material and compare it with the provided tools/toolsinvisibleladder_fix.vmt. Verify the replacement or override preserves the ladder texture while allowing transparency in Hammer and avoiding the VIS and compile-time issue described in the report.

Written by the indexing model from the issue text.