docs(openspec): add SDD artifact trail for recent alarm and EQ changes

Persist the exploration, proposal, spec, design, tasks, and
verify/archive reports produced during the multi-device EQ,
alarm-countdown, and notification-visual-polish SDD cycles.

openspec/changes/eq-device-autoswitch-ux/explore.md

@@ -0,0 +1,30 @@
+# Exploration: EQ Device Auto-Switch & Settings UX
+
+## Bug: EQ doesn't auto-switch on device connect/disconnect
+
+### Root Cause
+`EstadoEcualizador.cargarPersistido()` never calls `obtenerDispositivoActual()` at startup. `_dispositivoActualId` stays `null`, so `_resolverPresetActivo()` always returns `_presetPrincipal` (device preset never applied) until the next physical connect/disconnect event.
+
+### What works correctly
+Once `_dispositivoActualId` is set (via a stream event), `_onDispositivoCambiado()` correctly: sets ID, bootstraps first-seen device, re-resolves 4-level hierarchy, applies preset, notifies listeners.
+
+### Fix
+Call `obtenerDispositivoActual()` in `cargarPersistido()` after `_configurarSuscripcionDispositivo()` to seed initial device ID.
+
+## Feature: Settings Device List Improvements
+
+### Current state
+`_SeccionEcualizadorAvanzado` shows raw device IDs (`bt_a2dp:AA:BB:CC`) + preset name. No connection indicator, no renaming, no EQ editing.
+
+### Needed
+1. Connection status indicator (green dot if `entry.key == eq.dispositivoActualId`)
+2. Device custom name storage (`eq_nombres_dispositivos_v1` SP key)
+3. Display name fallback: `customName ?? platformName (non-empty) ?? deviceId`
+4. Modal bottom sheet for device editing: rename TextField + EcualizadorWidget
+5. Follows existing modal pattern: `showModalBottomSheet(showDragHandle: true, isScrollControlled: true)`
+
+## Affected Files
+- `lib/estado/estado_ecualizador.dart` — fix init + rename API
+- `lib/servicios/servicio_ecualizador.dart` — new SP key for names
+- `lib/pantallas/pantalla_ajustes.dart` — rewrite device section + new modal
+- Tests for all changes