Invalid characters in JS img tag prevent PDF placeholder thumbnail rendering

Problem/Motivation

PDF placeholder thumbnails are not rendering in the file browser grid/list view.

The JavaScript responsible for injecting the placeholder image contains invalid
middle-dot characters (·) instead of spaces inside the HTML string.
Because of this, the generated <img> tag is malformed
and not parsed correctly by the browser.

Problematic code:

$(thumbnailWrapper[i]).prepend(
  '<img·style="width:100px;·height:100px;"·src="/modules/contrib/file_browser/images/document_placeholder.svg"/>'
);

Steps to reproduce

1. Open the File Entity Browser widget.
2. Upload or select a PDF file.
3. Observe that no thumbnail placeholder icon is displayed.
4. Inspect the DOM and verify the image tag markup is invalid.

Proposed resolution

Replace the middle-dot characters with proper spaces in the HTML string.

$(thumbnailWrapper[i]).prepend(
  '<img style="width:100px; height:100px;" src="/modules/contrib/file_browser/images/document_placeholder.svg"/>'
);

Remaining tasks

• Replace invalid characters with spaces in the JavaScript file.
• Verify PDF placeholder thumbnails render correctly.
• Test across supported browsers.

User interface changes

• PDF files will display a placeholder thumbnail icon.
• No layout or workflow changes.

API changes

• None.

Data model changes

• None.