Simplify ExternalTable storage initialization

Remove lazy initialization pattern for storage attribute since it was being initialized in __init__ anyway. Storage is now a regular instance attribute instead of a property.

Author: claude

src/datajoint/external.py

@@ -39,7 +39,6 @@ class ExternalTable(Table):
  def __init__(self, connection, store, database):
  self.store = store
  self.spec = config.get_store_spec(store)
- self._storage = None
  self.database = database
  self._connection = connection
  self._heading = Heading(
@@ -54,7 +53,7 @@ def __init__(self, connection, store, database):
  if not self.is_declared:
  self.declare()
  # Initialize storage backend (validates configuration)
- _ = self.storage
+ self.storage = StorageBackend(self.spec)
 
  @property
  def definition(self):
@@ -73,13 +72,6 @@ def definition(self):
  def table_name(self):
  return f"{EXTERNAL_TABLE_ROOT}_{self.store}"
 
- @property
- def storage(self) -> StorageBackend:
- """Get or create the storage backend instance."""
- if self._storage is None:
- self._storage = StorageBackend(self.spec)
- return self._storage
-
  @property
  def s3(self):
  """Deprecated: Use storage property instead."""