Postprocessing - Code Checks

I know it's a big one, but code checks would be useful for various material types: steel, concrete, timber, and masonry. Building a whole Excel spreadsheet to do it, then manually import the results into it, is complex and time-consuming.

The issue does not name any files, tests, or entry points. First clarify the scope of code checks for steel, concrete, timber, and masonry, including the expected inputs and outputs and how results should replace the manual Excel workflow. Done should mean the agreed material checks are implemented and their results can be used without manual spreadsheet import.

Written by the indexing model from the issue text.