* views_api.py: This is where your public API would go. It will be exposed at "$DOMAIN/$PLUGIN/$ROUTE". For example: https://lnbits.com/mysuperplugin/api/v1/tools.
* views.py: The `/` path will show up as your plugin's home page in lnbits' UI. Other pages you can define yourself. The `templates` folder should explain itself in relation to this.
LNbits currently supports SQLite and PostgreSQL databases. There is a migration script `tools/conv.py` that helps users migrate from SQLite to PostgreSQL. This script also copies all extension databases to the new backend.
`mock_data.zip` contains a few lines of sample SQLite data and is used in automated GitHub test to see whether your migration in `conv.py` works. Run your extension and save a few lines of data into a SQLite `your_extension.sqlite3` file. Unzip `tests/data/mock_data.zip`, add `your_extension.sqlite3` and zip it again. Add the updated `mock_data.zip` to your PR.