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/core/components/fileEditor/FileEditorFileName.test.tsx

@@ -0,0 +1,53 @@
+import React from "react";
+import { describe, expect, test } from "vitest";
+import { render, screen } from "@testing-library/react";
+import { MantineProvider } from "@mantine/core";
+import FileEditorFileName from "@app/components/fileEditor/FileEditorFileName";
+import type { StirlingFileStub } from "@app/types/fileContext";
+import type { FileId } from "@app/types/file";
+
+const buildFileStub = (
+  overrides: Partial<StirlingFileStub> = {},
+): StirlingFileStub => ({
+  id: "file-1" as FileId,
+  name: "report.pdf",
+  type: "application/pdf",
+  size: 1024,
+  lastModified: 0,
+  isLeaf: true,
+  originalFileId: "file-1",
+  versionNumber: 1,
+  ...overrides,
+});
+
+const renderName = (file: StirlingFileStub) =>
+  render(
+    <MantineProvider>
+      <FileEditorFileName file={file} />
+    </MantineProvider>,
+  );
+
+describe("FileEditorFileName (core / web)", () => {
+  test.each([
+    { name: "not-saved", file: buildFileStub() },
+    {
+      name: "dirty",
+      file: buildFileStub({ localFilePath: "/tmp/report.pdf", isDirty: true }),
+    },
+    {
+      name: "saved",
+      file: buildFileStub({ localFilePath: "/tmp/report.pdf", isDirty: false }),
+    },
+  ])("does not render a save indicator ($name)", ({ file }) => {
+    renderName(file);
+
+    expect(screen.queryByLabelText("fileNotSavedToDisk")).toBeNull();
+    expect(screen.queryByLabelText("unsavedChanges")).toBeNull();
+    expect(screen.queryByLabelText("fileSavedToDisk")).toBeNull();
+  });
+
+  test("renders the filename", () => {
+    renderName(buildFileStub({ name: "invoice.pdf" }));
+    expect(screen.getByText("invoice.pdf")).toBeInTheDocument();
+  });
+});

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

@@ -1,13 +1,18 @@
 import React from "react";
 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) => (
-  <PrivateContent>{file.name}</PrivateContent>
+const FileEditorFileName = ({
+  file,
+  maxLength = 40,
+}: FileEditorFileNameProps) => (
+  <PrivateContent>{truncateCenter(file.name, maxLength)}</PrivateContent>
 );
 
 export default FileEditorFileName;

frontend/src/core/components/fileEditor/FileEditorThumbnail.tsx

@@ -45,7 +45,7 @@ import { PrivateContent } from "@app/components/shared/PrivateContent";
 import UploadToServerModal from "@app/components/shared/UploadToServerModal";
 import ShareFileModal from "@app/components/shared/ShareFileModal";
 import { useAppConfig } from "@app/contexts/AppConfigContext";
-import { truncateCenter } from "@app/utils/textUtils";
+import FileEditorFileName from "@app/components/fileEditor/FileEditorFileName";
 
 interface FileEditorThumbnailProps {
   file: StirlingFileStub;
@@ -580,8 +580,19 @@ const FileEditorThumbnail = ({
           marginBottom: "0.5rem",
         }}
       >
-        <Text size="lg" fw={700} className={styles.title} title={file.name}>
-          <PrivateContent>{truncateCenter(file.name, 40)}</PrivateContent>
+        <Text
+          size="lg"
+          fw={700}
+          className={styles.title}
+          title={file.name}
+          style={{
+            display: "flex",
+            alignItems: "center",
+            justifyContent: "center",
+            gap: "0.25rem",
+          }}
+        >
+          <FileEditorFileName file={file} />
         </Text>
         <Text
           size="sm"