Add cutout shell and volume node assets for depth volume processing

- Implemented `cutout_shell.py` to build front normals and shell positions for balloon geometry.
- Created `cutout_volume.py` to establish smooth center fields and manage balloon surface attributes.
- Introduced `pisa_sr_export.py` for exporting PiSA-SR components with dependencies and asset finalization.

src/anyimage/server/model_manager.py

@@ -1,4 +1,5 @@
 import gc
+import hashlib
 import time
 from pathlib import Path
 from types import SimpleNamespace
@@ -69,6 +70,9 @@ class ModelSessionCache:
     def get_upscale(self, model_dir, requested_device):
         from .models.onnx_upscale import create_session
 
+        if Path(model_dir).name == "pisa-sr":
+            from .models.onnx_pisa_sr import PisaSession as create_session
+
         key = (str(Path(model_dir).resolve()), requested_device, "onnx")
         if self.upscale_model is not None and self.upscale_key == key:
             return self.upscale_model
@@ -91,11 +95,17 @@ class ModelSessionCache:
         self._release_runtime_cache()
 
     def release_upscale(self):
+        close = getattr(self.upscale_model, "close", None)
+        if close is not None:
+            close()
         self.upscale_model = None
         self.upscale_key = None
         self._release_runtime_cache()
 
     def close(self):
+        close = getattr(self.upscale_model, "close", None)
+        if close is not None:
+            close()
         self.ben2_model = None
         self.da3_model = None
         self.moge_model = None
@@ -124,6 +134,7 @@ class ModelManager:
     def __init__(self, models_directory):
         self.models_directory = Path(models_directory)
         self.sessions = ModelSessionCache()
+        self.verified_files = {}
 
     def directory(self, model_key):
         model = model_catalog.get_downloadable_model(model_key)
@@ -132,6 +143,27 @@ class ModelManager:
     def ready(self, model_key):
         model = model_catalog.get_downloadable_model(model_key)
         directory = self.directory(model_key)
+        if model_key == "PISA_SR":
+            for filename, size, checksum in model.r2_files:
+                path = directory / filename
+                try:
+                    stat = path.stat()
+                    if stat.st_size != size:
+                        return False
+                    identity = (stat.st_size, stat.st_mtime_ns, stat.st_ctime_ns)
+                    cached = self.verified_files.get(path)
+                    # Windows can coalesce timestamps for immediately repeated writes.
+                    cacheable = size >= 1024 * 1024 and time.time_ns() - stat.st_mtime_ns > 1_000_000_000
+                    if not cacheable or cached != (identity, checksum):
+                        with path.open("rb") as stream:
+                            actual = hashlib.file_digest(stream, "sha256").hexdigest()
+                        if actual != checksum:
+                            return False
+                        if cacheable:
+                            self.verified_files[path] = (identity, checksum)
+                except OSError:
+                    return False
+            return True
         return all(any(directory.glob(pattern)) for pattern in model.ready_patterns)
 
     def get_ben2(self, model_dir, device):