Support Drag and Drop from Dock

[kickingvegas]

Support Drag and Drop by dragging URL icon from web browser to Captee icon in the dock.

[kickingvegas]

Some research:

System-Declared Uniform Type Identifiers
How does macOS tell the type of a file? – The Eclectic Light Company
Open a document: how it works, and where it can go wrong, 1: identification – The Eclectic Light Company
Supporting Drag and Drop Through File Promises | Apple Developer Documentation