Serialization callbacks and corpus warnings

ISerializationCallbackReceiver runs where Unity runs it (serialization_callbacks, 6000.3): after loaded fields (nested first), around Instantiate, in JsonUtility. Odin's SerializedMonoBehaviour fields now load through Odin's own DLLs (Minesweeper and SwampAttack start without exceptions).
BinaryFormatter saves load again: script contexts are the contextual reflection context, so Assembly.Load by name finds the scripts' assemblies; scripts get the working formatter package rather than the framework's stub.
Smaller corpus fixes: chars saved as numbers, base library types (TimeSpan) not serialized, ScriptableObjects in plugin DLLs (DOTween's settings), TouchInputModule, built-in materials 10301/10302/10306/10308 (by name from unity_builtin_extra), GIF and TIFF textures. Six projects lost all their warnings.
Next: ReadPixels from render textures; the Skybox component; other composite operations; effector forces; UI Toolkit (UnityChess).