docs(plugin): clarify ReadOnlySpan vs array usage in async/sync methods

- Add sync version of wave spawner using ReadOnlySpan<T> with ref readonly
- Clarify that async methods cannot use ReadOnlySpan (ref struct limitation)
- Note ReadOnlyMemory<T> as alternative for async with .Span access

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Signed-off-by: JasonXuDeveloper - 傑 <jason@xgamedev.net>

Author: JasonXuDeveloper

.claude-plugin/skills/game-patterns/SKILL.md

@@ -149,12 +149,14 @@ public sealed class ComboSystem : IDisposable
 
 ## Spawning Patterns
 
-### Wave Spawner (Async, Span)
+### Wave Spawner (Async)
 ```csharp
 public sealed class WaveSpawner
 {
     private readonly EnemySpawner _spawner;
 
+    // Use ReadOnlyMemory<T> for async (ReadOnlySpan<T> is a ref struct, invalid in async)
+    // Access .Span inside the loop for zero-allocation iteration
     public async UniTask RunWaves(ReadOnlyMemory<WaveConfig> waves, CancellationToken ct = default)
     {
         foreach (var wave in waves.Span)

.claude-plugin/skills/jaction/SKILL.md

@@ -182,6 +182,7 @@ public static async UniTaskVoid ApplyDoT(IDamageable target, float damage, int t
 
 ### Wave Spawner (Async)
 ```csharp
+// Async methods cannot use ReadOnlySpan (ref struct), use array instead
 public async UniTask RunWaves(WaveConfig[] waves)
 {
     foreach (var wave in waves)
@@ -197,6 +198,23 @@ public async UniTask RunWaves(WaveConfig[] waves)
         if (action.Cancelled) break;
     }
 }
+
+// Sync methods can use ReadOnlySpan for zero-allocation iteration
+public void RunWavesSync(ReadOnlySpan<WaveConfig> waves)
+{
+    foreach (ref readonly var wave in waves)
+    {
+        using var action = JAction.Create()
+            .Do(() => UI.ShowWaveStart(wave.Number))
+            .Delay(2f)
+            .Do(() => SpawnWave(wave))
+            .WaitUntil(() => ActiveEnemyCount == 0, timeout: 120f)
+            .Delay(wave.DelayAfter);
+        action.Execute();
+
+        if (action.Cancelled) break;
+    }
+}
 ```
 
 ### Health Regeneration (Zero-GC)