Recognize X100 bikes as VirtuFit Etappe 2.0i - #4906

Motivation

• Map physical devices advertising with the X100- Bluetooth name to the existing VirtuFit Etappe 2.0i behavior so X100 bikes behave like the VirtuFit Etappe device without requiring manual setting changes.

Description

• Treat devices whose Bluetooth name starts with X100- as fitplusbike in the central discovery logic by adding the X100- prefix check to bluetooth::deviceDiscovered (src/devices/bluetooth.cpp).
• Add an instance flag virtufitEtappe to fitplusbike (src/devices/fitplusbike/fitplusbike.h).
• Enable VirtuFit Etappe behavior automatically for X100 devices by setting virtufitEtappe = true when the device is discovered and OR-ing that flag with the existing virtufit_etappe QSettings checks across fitplusbike code paths (src/devices/fitplusbike/fitplusbike.cpp).
• Add a test/devicedata entry so the device-discovery test index contains a case for the X100- prefix (tst/Devices/devicetestdataindex.cpp) and register a device index value (tst/Devices/deviceindex.h / tst/Devices/deviceindex.cpp).

Testing

• Ran git diff --check to validate the patch formatting and it passed.
• Verified the new detection pattern and behavior gates via ripgrep searches for X100- and virtufit_etappe and found the expected edits in src/devices/bluetooth.cpp and src/devices/fitplusbike/fitplusbike.cpp respectively.
• Committed the changes (Add X100 VirtuFit Etappe bike detection) successfully; no CI tests were executed in this environment.
• Attempted qmake -v to run the Qt build/test suite but qmake is not available in the environment so the full test suite could not be run.

Codex Task