Migrate Hoarder/Karakeep to Linkwarden

Small helper that reshapes a Hoarder/Karakeep export into something Linkwarden’s importer accepts.

Usage

python3 convert.py hoarder-export.json --output linkwarden-import.json

• The script puts every link into a single Hoarder Import collection.
• Tags are copied exactly as they appear in the export.
• Optional flags: --user-id (defaults to 1) and --collection-color.