docs(spacemouse): rename device to SpaceMouse, describe GI as baked

docs(spacemouse): rename device to SpaceMouse, describe GI as baked

User-facing text and docs now say SpaceMouse, covering both the
SpaceNavigator over USB and the SpaceMouse Wireless over Bluetooth:
launcher entry, demo readout (including the no-device hint) and
javadoc. The manual's SpaceMouse section lists both transports.

Also correct the global illumination wording in HouseDemo and the
manual: GI is baked in bounce generations over the first seconds and
then frees its per-texel state, rather than progressing from
per-polygon stamps to per-texel refinement.