Typed signatures with Latin extended characters fall back to Noto Sans instead of Caveat

Issue Description

When a recipient enters a typed signature containing non-ASCII Latin characters (such as Polish diacritics ą, ć, ę, ł, ń, ó, ś, ź, ż, German umlauts ä, ö, ü, French accents é, è, ç, Scandinavian letters ø, å, etc.), the signature on the signed document canvas and in the generated PDF falls back to plain Noto Sans instead of using the handwriting font Caveat.

✅ Caveat font file already contains full coverage for Latin Extended-A (and Cyrillic). Typing such characters in the signature modal input renders them properly in Caveat in the browser em

⚠️ However, these characters are blocked in document view.

In many countries, names contain these characters, which should be fixed.

Steps to Reproduce

1. Open any document signing link (/sign/{token}).
2. Click on a signature field and select the Type signature tab.
3. Type a name containing Latin extended / accented characters (e.g., Michał Bąk, François Müller, or Jørgen).
4. Complete the signing and check the rendered signature on the document canvas or the exported PDF.

Expected Behavior

Names using Latin characters supported by Caveat should render using the handwriting font Caveat.

Current Behavior

Any non-ASCII character triggers the isASCII check to return false, immediately falling back to: "Noto Sans", "Noto Sans Chinese", "Noto Sans Japanese", "Noto Sans Korean", sans-serif.

Screenshots (optional)

No response

Operating System [e.g., Windows 10]

Windows 11

Browser [e.g., Chrome, Firefox]

Chrome 152

Version [e.g., 2.13.0]

v2.18.0

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