The HTTP port and on-device paths for the SoundTouch speaker were
duplicated across pkg/client (unexported) and pkg/service/constants
(under a service-layer prefix). Both spots needed the same values, and
the next round of work (group/persistence handling in the CLI) would
have created a third — or worse, dragged pkg/service into the CLI's
dependency graph just for a port number.
pkg/speaker is a no-deps leaf that holds the speaker-protocol
constants: HTTPPort, the request paths, and the on-device persistence
file locations (now including GroupServiceFileLocation, for the
upcoming stereo-pair sync work). The client library, the service, the
CLI, and tests can all import it without introducing a layering edge.
This commit moves nothing into pkg/speaker that doesn't belong there —
the service-specific constants (provider IDs, file names, date stub,
etc.) stay in pkg/service/constants. Only the genuinely
protocol-level values move.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>