The equalizer's preset-cycling custom action (eq_preset_siguiente) and
its ic_auto_eq_preset drawable are no longer needed now that the
"Ecualizador" folder lists all six presets directly: the folder replaces
what the cycle action did, and this frees a scarce Android Auto custom
action slot.
The on/off toggle is now the equalizer's only custom action.
On a car head unit the custom actions render icon-first, so two actions
sharing ic_stat_pluriwave were indistinguishable and the toggle gave no
sign of whether the equalizer was on.
Each action now has its own drawable, and the toggle swaps between
ic_auto_eq_on and ic_auto_eq_off so its state is legible at a glance.
Expose the equalizer's on/off toggle and preset choice as PlaybackStateCompat
custom actions on the now-playing screen. The redesign's removal of the
in-car equalizer FOLDER from the browse tree stays as-is (2403da3) -- this
is a different surface (playback screen custom actions, not a browse
folder) and does not reintroduce it.
Deliberately just 2 actions -- an on/off toggle plus a cycling preset
action, not one action per preset -- since Android Auto only surfaces a
limited number of custom actions. Both reuse the existing
setEcualizadorActivo/aplicarPreset entry points (the same ones
EstadoEcualizador's phone settings screen uses), so a car tap and a phone
tap behave identically and both keep the action labels in sync. Reuses the
bundled ic_stat_pluriwave drawable (the notification's own equalizer-bars
icon) -- zero new native assets. The 5-band constraint is untouched.
New pure, unit-tested functions in servicio_audio.dart: presetSiguiente,
nombrePresetVisible, controlesEcualizadorPersonalizados. New ARB keys
(eqCustomActionEnableLabel/DisableLabel/PresetLabel) across all 13 locales,
regenerated via flutter gen-l10n.