Release 2.0.1-beta3

Fixes effects on segment-based IOTBT devices (e.g. the IOTBT6BA corner lamp from #83).

The 0xE1 0x01 effect command was malformed since the feature was added (off-by-one before the palette header, wrong palette-length byte, and a fixed palette regardless of the selected effect), so effects did nothing while colour and brightness worked. The command is now rebuilt to match the app, with per-effect palettes captured for several scenes and a sensible default for the rest.

Scope: this only affects segment IOTBT devices; all other device families use separate effect commands and are unchanged.

See betatest.md for how to install and test a beta.