PDF-Title (export) should be document title

[benjaminseidler]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:

1. Menu
2. Export PDF
3. Print
4. File save dialoge opens: suggested file-name: tauri.localhost.pdf

Expected behavior
Suggested file-name: document-title.pdf (from .md-filename)

Device

• OS: Windows
• Version: 11
• App Version : 2.6.4