fix: forward billing-v2 protocol on textchat KB retrieval and node summaries (#503)

Two call sites dropped the MPS billing-v2 protocol, so orgs on model
config v2 got 400 "Service Key uses billing v2" from MPS:

- text_chat_runner built PipecatEngine without embeddings_provider
  (extracted but never passed), so knowledge-base retrieval fell through
  to the plain OpenAI-compatible client instead of DograhEmbeddingService
  and sent no correlation_id/mps_billing_version metadata. Also pass
  endpoint/api_version for Azure BYOK parity with run_pipeline.
- node_summary built its QA LLM without the run's correlation id, unlike
  its sibling call in qa/analysis.py.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

api/services/workflow/text_chat_runner.py

@@ -532,6 +532,9 @@ async def execute_text_chat_pending_turn(
     embeddings_api_key = None
     embeddings_model = None
     embeddings_base_url = None
+    embeddings_provider = None
+    embeddings_endpoint = None
+    embeddings_api_version = None
     if user_config.embeddings:
         from api.services.configuration.ai_model_configuration import (
             apply_managed_embeddings_base_url,
@@ -544,6 +547,8 @@ async def execute_text_chat_pending_turn(
             provider=embeddings_provider,
             base_url=getattr(user_config.embeddings, "base_url", None),
         )
+        embeddings_endpoint = getattr(user_config.embeddings, "endpoint", None)
+        embeddings_api_version = getattr(user_config.embeddings, "api_version", None)
 
     has_recordings = await db_client.has_active_recordings(workflow.organization_id)
     context_compaction_enabled = (workflow.workflow_configurations or {}).get(
@@ -560,6 +565,9 @@ async def execute_text_chat_pending_turn(
         embeddings_api_key=embeddings_api_key,
         embeddings_model=embeddings_model,
         embeddings_base_url=embeddings_base_url,
+        embeddings_provider=embeddings_provider,
+        embeddings_endpoint=embeddings_endpoint,
+        embeddings_api_version=embeddings_api_version,
         has_recordings=has_recordings,
         context_compaction_enabled=context_compaction_enabled,
     )