Add get_transfer() and cancel_transfer() for file transfer monitoring

[heikkih]

Summary

Adds two methods wrapping the /api/v1/transfer endpoint:

• get_transfer() -> Transfer | None — returns the active transfer, or None on 204 (no transfer in progress)
• cancel_transfer(transfer_id: int) -> None — stops an active transfer via DELETE /api/v1/transfer/{id}

The Transfer TypedDict covers all fields from the OpenAPI spec. All fields are optional (total=False) since availability varies by transfer state and direction. The id field is not in the spec schema but is included as it is needed to call cancel_transfer().

Test plan

• test_get_transfer — verifies fields from a 200 response
• test_get_transfer_none — verifies None is returned on 204
• test_cancel_transfer — verifies correct URL is called

🤖 Generated with Claude Code

[heikkih]

Pushed c37af23 — total=False removed, NotRequired applied per the OpenAPI spec's required list:

Required: type, display_name, path, progress, transferred, time_transferring, to_print
NotRequired: id (printer-returned but not in spec), url (only for FROM_WEB), size, time_remaining

[agners]

This needs rebasing/merge now.

[heikkih]

Pushed 7c42fb0:

• size typed as NotRequired[str] matching the OpenAPI spec
• Mock test response uses "2393142" (string) for consistency
• Rebased onto current main (Storage from Add get_storage() to query available storage devices #159 included)

[agners]

LGTM!