Drop default action delay back to 4 seconds

PR #226 had bumped the default from 4s to 6s as a hedge against Android shuffling the BT stream volume late during route setup. On-device verification with AirPods Pro 2 on a Pixel 8 shows the route is stable well before 4s elapse and volume changes land at the intended target with no shuffle. Two seconds shaved off the typical connect-to-stable time for users who never customized actionDelay.

Author: d4rken

app/src/main/java/eu/darken/bluemusic/devices/core/ManagedDevice.kt

@@ -103,10 +103,7 @@ data class ManagedDevice(
         return null
     }
 
-    // 6s is the global settle barrier window for devices without a user-configured override.
-    // Post per-module-delay collapse this is the only "wait for BT route to stabilize"
-    // window most pipelines pay; previously each module independently waited 4s of its own.
-    private val defaultActionDelay: Duration = Duration.ofSeconds(6)
+    private val defaultActionDelay: Duration = Duration.ofSeconds(4)
     private val defaultMonitoringDuration: Duration = Duration.ofSeconds(4)
     private val defaultAdjustmentDelay: Duration = Duration.ofMillis(250)
 

app/src/test/java/eu/darken/bluemusic/devices/core/ManagedDeviceTest.kt

@@ -266,8 +266,8 @@ class ManagedDeviceTest : BaseTest() {
     }
 
     @Test
-    fun `actionDelay defaults to 6s when null`() {
-        create().actionDelay shouldBe Duration.ofSeconds(6)
+    fun `actionDelay defaults to 4s when null`() {
+        create().actionDelay shouldBe Duration.ofSeconds(4)
     }
 
     @Test