idle stepper: add Use Stepper enable toggle (mini6ch, core)

The Stepper panel appeared but had no way to enable it: every stepper
field was gated on useStepperIdle while no field set it. Add the
'Use Stepper' toggle (useStepperIdle) to the idlehw dialog and the
'panel = idleStepper' entry to idleHwType, matching the official
rusEFI layout. UI-only change, no firmware rebuild needed.

Author: amrikarisma

CHANGELOG.md

@@ -28,7 +28,7 @@ All notable changes to Mazduino firmware are documented here.
 - mazduino-compact: second idle solenoid field corrected to `secondSolenoidPin`
 - mazduino-lite: knock disabled by leaving `EFI_SOFTWARE_KNOCK` undefined (not set to FALSE) so `#ifdef` guards evaluate correctly
 - mazduino-mini6ch: `ts_show_traction_control true` enabled as ETB-capable board is the only variant that supports traction control
-- mazduino-mini6ch: stepper idle valve exposed in TunerStudio — added `panel = idleStepper` to the `idleHwType` (Idle Valve Hardware) dialog in the generated INI so the Stepper option appears alongside Solenoid; no firmware rebuild required since the stepper config fields already exist at fixed offsets
+- mazduino-mini6ch and mazduino-core: stepper idle valve exposed in TunerStudio — added `panel = idleStepper` to the `idleHwType` (Idle Valve Hardware) dialog and the `Use Stepper` enable toggle (`useStepperIdle`) to the `idlehw` dialog in the generated INI, matching the official rusEFI layout; the Stepper option now appears alongside Solenoid with a working enable/disable control. No firmware rebuild required since the stepper config fields already exist at fixed offsets. Intentionally left hidden on mazduino-lite and mazduino-compact (hardware does not support stepper idle)
 - Dockerfile updated to handle both `ports.ubuntu.com` (ARM64) and `archive.ubuntu.com` (x86-64) Ubuntu mirror replacements for EOL Mantic release
 
 ### Removed

generated/tunerstudio/generated/rusefi_mazduino-mini6ch.ini

@@ -11302,6 +11302,7 @@ dialog = allPinsOutputs_1_and_2, "", xAxis
 	dialog = idlehw, "", yAxis
 		topicHelp = "idlehwHelp"
 		field = "!ECU reboot needed to apply these settings"
+		field = "Use Stepper",							useStepperIdle
 		field = "Electronic throttle idle range",			etbIdleThrottleRange
 		panel = idleHwType