Refactor core APIs, fix bugs, and improve safety

- Make image result/info structs readonly; improve error handling and memory safety in image library
- Introduce IJobScheduler interface; move job scheduling docs to interface
- Remove "index 0 invalid" convention from slot/sparse maps; fix Count logic
- Add Owner<T> for disposable value types in low-level utilities
- Improve ObjectPool<T> thread safety and logic
- Change List<T>.RemoveAndSwapBack to return bool
- Remove unsafe methods from generated math types; add debug range checks
- Update benchmarks and enable collection checks in tests
- Improve documentation, comments, and error messages
- Bump assembly versions across all projects

Misaki.HighPerformance.Image/AnimatedFrameResult.cs

@@ -1,9 +1,14 @@
-namespace Misaki.HighPerformance.Image;
+namespace Misaki.HighPerformance.Image;
 
-public class AnimatedFrameResult : ImageResult
+public readonly struct AnimatedFrameResult
 {
+    public required ImageResult Image
+    {
+        get; init;
+    }
+
     public int DelayInMs
     {
-        get; set;
+        get; init;
     }
-}
+}