[asdolo]

Summary

• Each button assigned Gestures keeps its own up/down/left/right/click map (Options+-style), instead of one shared profile-wide Gestures section.
• Legacy flat [Gestures] profiles migrate by copying the shared map onto every gesture-trigger button.
• Assigning Gestures to a button for the first time seeds that button from device defaultGestures.

Test plan

• Assign Gestures to two buttons; change a direction on one — the other must stay unchanged
• Restart app / reload profile — per-button bindings persist under [Gestures/<buttonIndex>/…]
• Open an older profile with flat [Gestures] keys — both gesture buttons still work, then diverge after editing
• logitune-tests filters for *Gesture*, ProfileEngine.*, DeviceModelTest.*Gesture* pass

[mmaher88]

Thanks, this closes #122 nicely, and the migration from the old flat [Gestures] keys and its tests are solid. Since #174 landed, a few things need attention on rebase:

1. ButtonActionDispatcher.cpp merges without a git conflict but still uses m_currentDevice, which no longer exists. Instead of looking up a descriptor on release, please record the button index in the per-device state when the gesture button is pressed and use that.
2. In setupProfileForDevice, seed from the connecting device's descriptor, not m_currentDevice.
3. Update tests/test_device_routing.cpp, which still uses .gestures.
4. In saveCurrentProfile, move p.buttonGestures.clear() inside the m_currentDevice guard, so a save without a descriptor can't wipe every map.

For downgrades, could you keep writing the flat [Gestures] keys (mirroring the lowest gesture button) for a release or two? Older builds would then keep working instead of erasing the nested keys on their next save. If #168 merges first, please route its drag path through the same per-button lookup.