Fix missing desktop save indicator on files (#6310)

# Description of Changes
Save indicator stopped showing up after #6050, which fixed the missing
truncation on filenames, but accidentally bypassed the save indicator
component at the same time. This PR puts the component back in and makes
it support truncation so we can have both.

<img width="586" height="166" alt="image"
src="https://github.com/user-attachments/assets/529c3dcb-ee00-4a6d-ae53-ef8657204369"
/>

frontend/src/desktop/components/fileEditor/FileEditorFileName.tsx

@@ -3,17 +3,22 @@ import { Tooltip } from "@mantine/core";
 import { useTranslation } from "react-i18next";
 import { StirlingFileStub } from "@app/types/fileContext";
 import { PrivateContent } from "@app/components/shared/PrivateContent";
+import { truncateCenter } from "@app/utils/textUtils";
 
 interface FileEditorFileNameProps {
   file: StirlingFileStub;
+  maxLength?: number;
 }
 
-const FileEditorFileName = ({ file }: FileEditorFileNameProps) => {
+const FileEditorFileName = ({
+  file,
+  maxLength = 40,
+}: FileEditorFileNameProps) => {
   const { t } = useTranslation();
 
   return (
     <>
-      <PrivateContent>{file.name}</PrivateContent>
+      <PrivateContent>{truncateCenter(file.name, maxLength)}</PrivateContent>
       {!file.localFilePath && (
         <Tooltip label={t("fileNotSavedToDisk", "Not saved to disk")}>
           <span