Start the protocol tree: wire protocols move to library/protocol/<name>/,
entry file <name>-protocol.zig, module name unchanged. block and usb-transfer
are pure moves — every consumer already imports them by module name, so only
the b.addModule paths change and the empty system/services/block/ is removed.
block-protocol -> library/protocol/block/block-protocol.zig
usb-transfer-protocol -> library/protocol/usb-transfer/usb-transfer-protocol.zig
zig build + test green.
Daniel Samson
f90dc6c121