check Nushell files in the CI (!137)

in order to help catch issues with the various Nushell scripts and modules in the source base, i propose to add a CI script that will check them all.

below is an example error, e.g. when introducing a syntax error in `.env.nu`:
```
Error:   × Failed to parse content:
  │     file: .env.nu
  │     err:  Expected keyword.
```

Makefile

@@ -9,6 +9,7 @@ fmt:
 	cargo fmt --all
 
 check:
+	nu scripts/check-nushell-files.nu
 	cargo check --workspace --all-targets
 	cargo check --workspace --all-targets --features kzg
 	cargo check --workspace --all-targets --features aplonk

scripts/check-nushell-files.nu

+let files = ^git lf | lines | where { ($in | path parse).extension == "nu" }
+
+for f in $files {
+    let path = $env.FILE_PWD | path dirname | path join $f
+
+    try {
+        nu-check $path --debug
+    } catch { |e|
+        let err = $e.debug
+            | ansi strip
+            | parse --regex '(.*)msg: "Found : (?<msg>.*)", span: (?<span>.*)'
+            | into record
+
+        error make --unspanned {
+            msg: ([
+                $"(ansi red_bold)($e.msg)(ansi reset):",
+                $"    file: (ansi purple)($f)(ansi reset)",
+                $"    err:  ($err.msg)",
+            ] | str join "\n")
+        }
+    }
+}