Zig isn't Rust, so it makes sense that patterns in Rust don't translate well, but also I totally get TFA's preference for Rust in this case.
I thought the value of const was once you read const x = 1024, you can be sure that x is 1024 while its in scope, that subsequent code can make assumptions about the content of variable x. Or, when you see x in the code, you can jump directly to its definition and know what its value will be. Defined once and not changed.
Apparently I don't understand the value of const at all.
If you have shadowing, it simply means you can have a different variable with the same name later in the same (or child) scope, this usually must be explicit. The same name now refers to a different variable, but the original variable still exists and remains valid.
It's quite a useful pattern, particularly where the old value is no longer useful (for example transforming input), especially when using the old value might be valid code but would be a mistake.