fix(server): don't crash when the proxy port is still in use

CIO reports a failed bind from its accept coroutine; unhandled, that
exception terminates the process on Kotlin/Native before the port fallback
can run, so relaunching iOS shortly after playback crashed (EADDRINUSE).
Contain it with a parent CoroutineExceptionHandler and enable reuseAddress
so the preferred port can be rebound while old connections are in TIME_WAIT.

composeApp/src/commonMain/kotlin/org/spotube/spotube/core/server/ServerBinder.kt

@@ -21,7 +21,10 @@ package org.spotube.spotube.core.server
 import io.ktor.server.application.Application
 import io.ktor.server.cio.CIO
 import io.ktor.server.engine.EmbeddedServer
+import io.ktor.server.engine.connector
 import io.ktor.server.engine.embeddedServer
+import io.ktor.server.application.serverConfig
+import kotlinx.coroutines.CoroutineExceptionHandler
 import kotlinx.coroutines.currentCoroutineContext
 import kotlinx.coroutines.ensureActive
 import kotlinx.coroutines.withTimeout
@@ -37,6 +40,9 @@ internal class BoundServer(val engine: EmbeddedServer<*, *>, val port: Int, val
  * preferred port can't be bound, retry on an OS-assigned free port (port 0).
  *
  * The caller must read [BoundServer.port] instead of assuming [preferredPort].
+ *
+ * `reuseAddress` lets a restarted app rebind its old port while connections from the previous
+ * run (e.g. the player's) are still in TIME_WAIT.
  */
 internal suspend fun startServerWithPortFallback(
     host: String,
@@ -47,8 +53,25 @@ internal suspend fun startServerWithPortFallback(
     val candidates = listOf(preferredPort, 0).distinct()
     var lastFailure: Throwable? = null
 
+    // CIO reports a failed bind from its accept coroutine. Unhandled, that exception kills the
+    // process on Kotlin/Native (iOS) before the fallback below gets to run; the failure still
+    // reaches us through resolvedConnectors(), so it only needs to be contained here.
+    val swallowBindFailure = CoroutineExceptionHandler { _, _ -> }
+
     for (candidate in candidates) {
-        val engine = embeddedServer(factory = CIO, host = host, port = candidate, module = module)
+        val engine = embeddedServer(
+            factory = CIO,
+            rootConfig = serverConfig {
+                parentCoroutineContext = swallowBindFailure
+                module { module() }
+            },
+            configure = {
+                connector {
+                    this.host = host
+                    this.port = candidate
+                }
+                reuseAddress = true
+            })
         try {
             engine.start(wait = false)
             val boundPort = withTimeout(5.seconds) { engine.engine.resolvedConnectors().first().port }