fix(android): extract OfflineGatedDataSource gate to satisfy detekt ThrowsCount

The added IOException rethrow pushed open() to 3 throws (max 2). Move the
two gating throws into a private gateOnHealth() helper.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

android/app/src/main/java/com/fabledsword/minstrel/player/OfflineGatedDataSource.kt

@@ -26,6 +26,19 @@ class OfflineGatedDataSource(
 ) : DataSource {
 
     override fun open(dataSpec: DataSpec): Long {
+        gateOnHealth()
+        return try {
+            val opened = delegate.open(dataSpec)
+            health.reportSuccess() // bytes flowing from the server == reachable
+            opened
+        } catch (e: IOException) {
+            health.reportFailure() // real network read failed → arbitrate via /healthz
+            throw e
+        }
+    }
+
+    /** Fast-fail before touching the network when the server can't be reached. */
+    private fun gateOnHealth() {
         when (health.state.value) {
             ServerHealth.Offline -> throw OfflineException(
                 "Track not in the on-device cache and the device is offline.",
@@ -36,14 +49,6 @@ class OfflineGatedDataSource(
             // Unstable is non-gating: still try the network. Healthy too.
             ServerHealth.Unstable, ServerHealth.Healthy -> Unit
         }
-        return try {
-            val opened = delegate.open(dataSpec)
-            health.reportSuccess() // bytes flowing from the server == reachable
-            opened
-        } catch (e: IOException) {
-            health.reportFailure() // real network read failed → arbitrate via /healthz
-            throw e
-        }
     }
 
     override fun close() = delegate.close()