A richer first run, plus a cleaner export.

- Fresh installs now come with six real sample notes that show off Markdown, journaling, project notes, tags/search/backlinks, and folder sync. Browse them, then delete when you're ready.
- Fixed a problem where exporting a note to PDF or Markdown printed the title twice. Notes now export exactly as written, with the title shown once.

Your existing notes and highlights are untouched.
