deep-hash -> hash

[andrew4328]

Describe your changes

Features:

• deep-hash -> hash, if you need to hash a flat memory segment then erase the type down to a Sized span
• Nil type can also be written as ()
• fix a bug where printing to stdout wouldn't interleave naturally due to fputs buffer and direct write
• fix a tokenization bug where __ was treated special, which breaks normal identifiers like __unidentified
• allow Nil, Never, and C<"void"> as variable bindings in all positions

Issue ticket number and link

#1878

Checklist before requesting a review

• [ x ] I have performed an AI-assisted self-review of my code.

Can you review my pull request and provide some suggestions?
https://patch-diff.githubusercontent.com/raw/Lambda-Mountain-Compiler-Backend/lambda-mountain/pull/1926.diff

• [ x ] If it is a new feature, I have added thorough tests.
• [ x ] I agree to release these changes under the terms of the permissive MIT license (1).

1. https://github.com/andrew-johnson-4/lambda-mountain/blob/main/LICENSE