Add support for extensionless Python files for server (#13326)

## Summary

Closes: #12539 

## Test Plan

https://github.com/user-attachments/assets/e49b2669-6f12-4684-9e45-a3321b19b659

crates/ruff_server/src/fix.rs

@@ -38,6 +38,7 @@ pub(crate) fn fix_all(
             file_resolver_settings,
             Some(linter_settings),
             None,
+            query.text_document_language_id(),
         ) {
             return Ok(Fixes::default());
         }