Tracking laminated file state

Nobody has claimed this yet.

In order to take advantage of lamination semantics, we first need to track the boolean state as to whether a file has been laminated. For example, this could be a new boolean field on the global file metadata.

Knowing whether a file is laminated will greatly assist in things like file size queries:

```
get_file_size() {
if (laminated)
return cached_file_size (cheap)
else
query key/value store for current max written offset (expensive)
}
```

We can also start to return errors on new writes.

To set the laminated property, we may need to define the unifycr_laminate function in our library.

Start by locating the global file metadata and the library entry point for the proposed unifycr_laminate function. Trace how lamination state would affect get_file_size and new writes. Done means the boolean state is tracked consistently and the intended post-lamination behavior is covered by relevant tests.

Written by the indexing model from the issue text.