[Tunes] Add missing iOS tiltback ERPM fields

[KozakBartosz]

What to build

Restore Android/iOS native parity for Refloat Tune Snapshot decoding by adding the missing tiltback_constant_erpm and tiltback_variable_erpm field definitions to the iOS Refloat tune group.

The iOS decoder must expose these values when the board-provided Refloat schema contains them and preserve existing compatibility behavior when an older schema omits them.

Likely files

• modules/vesc-ble/ios/RefloatConfigModels.swift - iOS REFLOAT_TUNE_GROUPS definition missing both fields.
• modules/vesc-ble/android/src/main/java/expo/modules/vescble/RefloatConfigModels.kt - parity reference containing the expected IDs, labels, units, and ordering.
• modules/vesc-ble/ios/RefloatConfigDecoder.swift - existing schema-driven omission and missingFieldIds behavior to verify.
• modules/vesc-ble/ios/Tests/ - likely location for native decoder/model parity coverage; inspect existing test structure first.

Implementation hints

• Preserve the field order used by Android: tiltback_constant, tiltback_constant_erpm, tiltback_variable, tiltback_variable_max, tiltback_variable_erpm.
• Match Android labels and units exactly.
• Do not make either ERPM field mandatory. RefloatConfigDecoder already skips definitions absent from a board schema and records their IDs in missingFieldIds.
• Inspect both files linked by the existing @parity annotations before finishing.

Acceptance criteria

• iOS REFLOAT_TUNE_GROUPS includes tiltback_constant_erpm with label Constant Tiltback ERPM and unit ERPM.
• iOS REFLOAT_TUNE_GROUPS includes tiltback_variable_erpm with label Variable Tiltback Start ERPM and unit ERPM.
• iOS field IDs, labels, units, and ordering match Android.
• Decoding a schema containing these fields exposes both values in the Tune Snapshot.
• Decoding an older schema without these fields still succeeds and reports them through missingFieldIds.
• Relevant iOS native tests pass.

Blocked by

None - can start immediately

Related

None