feat: Implement upscale functionality with ONNX models

- Added upscale operator to handle image upscaling by 4x using AI models.
- Introduced new jobs for upscale processing in the server, including debug and standard upscale jobs.
- Created a new ONNX model handler for upscale operations, supporting tiled inference and resource management.
- Updated tests to cover new upscale functionality, including input validation and output verification.
- Added documentation for the upscale feature, detailing usage and model options.

src/anyimage/server/models/__init__.py

@@ -1,4 +1,4 @@
-from . import ben2, da3, moge2, realesrgan
+from . import ben2, da3, moge2, upscale
 
 
 def geometry_adapter(model_key):
@@ -9,6 +9,6 @@ __all__ = (
     "ben2",
     "da3",
     "moge2",
-    "realesrgan",
+    "upscale",
     "geometry_adapter",
 )