feat(nodes): add ItemStorageMemory

The sqlite item storage class can be swapped for this eliminate costly network calls.

invokeai/app/services/item_storage/item_storage_memory.py

@@ -0,0 +1,42 @@
+from typing import Generic, Optional, TypeVar
+
+from pydantic import BaseModel
+
+from invokeai.app.services.item_storage.item_storage_base import ItemStorageABC
+from invokeai.app.services.shared.pagination import PaginatedResults
+
+T = TypeVar("T", bound=BaseModel)
+
+
+class ItemStorageMemory(ItemStorageABC, Generic[T]):
+    def __init__(self, id_field: str = "id") -> None:
+        super().__init__()
+        self._id_field = id_field
+        self._items: dict[str, T] = {}
+
+    def get(self, item_id: str) -> Optional[T]:
+        return self._items.get(item_id)
+
+    def set(self, item: T) -> None:
+        self._items[getattr(item, self._id_field)] = item
+        self._on_changed(item)
+
+    def delete(self, item_id: str) -> None:
+        try:
+            del self._items[item_id]
+            self._on_deleted(item_id)
+        except KeyError:
+            pass
+
+    def list(self, page: int = 0, per_page: int = 10) -> PaginatedResults[T]:
+        # TODO: actually paginate?
+        return PaginatedResults(
+            items=list(self._items.values()), page=page, per_page=per_page, pages=1, total=len(self._items)
+        )
+
+    def search(self, query: str, page: int = 0, per_page: int = 10) -> PaginatedResults[T]:
+        # TODO: actually paginate?
+        # TODO: actually search?
+        return PaginatedResults(
+            items=list(self._items.values()), page=page, per_page=per_page, pages=1, total=len(self._items)
+        )