Enhancement: Support for Custom Notiq File Type (`.ntq`)

[kilianbalaguer]

✨ Enhancement: Support for Custom Notiq File Type (.ntq)

Summary
Introduce a custom file type (.ntq) for saving and sharing notes outside of the app. This will allow users to export/import their notes (and eventually attachments) as a portable file, and support opening these files directly in Notiq.

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Motivation

• Enable users to back up and share notes easily.
• Allow exporting individual notes or collections.
• Lay groundwork for iCloud Drive / Files app integration.
• Potential future compatibility with third-party apps or a web client.

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Goals

1. Define a custom file extension .ntq for Notiq.
2. Implement export logic:
   • Export single note → .ntq file.
   • Export multiple notes (maybe zipped .ntqbundle).
3. Implement import logic:
   • Tap or drag .ntq file → open in Notiq.
   • Parse JSON or Core Data serialized format.
4. Register file type with Uniform Type Identifier (UTI) for iOS/macOS:
   • Make .ntq files recognizable by system.
   • Associate with Notiq app icon.
5. Integrate with Share Sheet / Files App.

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Technical Notes

• Use Codable to serialize/deserialize note objects.
• Consider versioning the file format for forward compatibility.
• Storage format:
  • note.json → text content, metadata (id, title, date, tags).
  • Attachments (images, drawings, audio) could be stored in a bundle folder later.
• Use UIDocumentPickerViewController (iOS) / NSOpenPanel (macOS) for import/export.

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Future Expansion

• Bundle multiple notes + media → .ntqpackage (like Pages or Keynote bundles).
• iCloud Drive syncing of .ntq files for universal access.
• Cross-platform compatibility (Windows/Linux/Android later).