Function useDocument

Tracks the active CAD document and its open lifecycle for UI consumers.

This composable centralizes reactive document metadata from AcApDocManager and AcApDocument, including:

• Current or pending document open mode
• Whether a document open operation is in progress
• Current document file name and display title

Behavior:

• Initializes from the currently active document once the viewer exists
• Retries binding after mount when the viewer has not been created yet
• Updates openMode as soon as documentToBeOpened fires
• Synchronizes fileName, docTitle, and openMode when documentActivated fires
• Clears the opening state when failed-to-open-file is emitted
• Records lastOpenErrorCode from structured open failures