Move _operation_context init to _ODataBase to eliminate duplication

Both sync and async clients had identical 2-line initialization:
  ctx_obj = self.config.operation_context
  self._operation_context = ctx_obj.user_agent_context if ctx_obj else None

Since self.config is already available in _ODataBase.__init__, this
belongs in the base class. Subclasses inherit it and use it when
building the User-Agent header.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Abel Milash

src/PowerPlatform/Dataverse/data/_odata.py

@@ -81,9 +81,6 @@ def __init__(
             session=session,
             logger=self._http_logger,
         )
-        ctx_obj = self.config.operation_context
-        self._operation_context = ctx_obj.user_agent_context if ctx_obj else None
-
     def close(self) -> None:
         """Close the OData client and release resources.
 

src/PowerPlatform/Dataverse/data/_odata_base.py

@@ -142,6 +142,8 @@ def __init__(self, base_url: str, config=None) -> None:
         self._logical_primaryid_cache: dict[str, str] = {}
         self._picklist_label_cache: dict[str, dict] = {}
         self._picklist_cache_ttl_seconds = 3600  # 1 hour TTL
+        ctx_obj = self.config.operation_context
+        self._operation_context: Optional[str] = ctx_obj.user_agent_context if ctx_obj else None
         self._http_logger = None
         if self.config.log_config is not None:
             from ..core._http_logger import _HttpLogger