Just: keep this directory's formatter to the file it was given

The recipe took the argument but also let just change directory into its own,
so a file named below it was looked for twice over. Interpolating the argument
raw split paths containing spaces as well. The shared formatters already avoid
both.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: redsun82

misc/just/justfile

@@ -1,2 +1,4 @@
+[no-cd]
+[positional-arguments]
 format *ARGS=".":
-    npx prettier --write {{ ARGS }}
+    npx prettier --write "$@"