fix(search-service): Pass structured_answer through SearchOutput (#632)

* fix(search-service): Pass structured_answer through SearchOutput

Add structured_answer field to SearchOutput creation to ensure citations
and structured output data flows through the search pipeline.

**Changes:**

1. **SearchOutput Creation** (search_service.py:586):
   - Add `structured_answer=result_context.structured_answer` to SearchOutput
   - Ensures structured output (with citations) is included in search results
   - Previously: Field existed in schema but not populated from result_context

2. **Debug Logging**:
   - Log document_metadata count before SearchOutput creation
   - Log first document name for debugging
   - Helps track data flow through search pipeline

**Why This Matters:**

- SearchOutput schema has `structured_answer: StructuredAnswer | None` field
- generation_stage.py creates structured output and adds to result_context
- But SearchService wasn't passing it through to SearchOutput
- Result: Structured output generated but lost before returning to caller

**Data Flow:**

```
generation_stage.py
    ↓
result_context.structured_answer = StructuredAnswer(...)
    ↓
SearchService._search_with_executor()
    ↓
SearchOutput(
    answer=...,
    documents=...,
    structured_answer=result_context.structured_answer  ← ADDED
)
    ↓
MessageProcessingOrchestrator
    ↓
Frontend (citations display)
```

**Testing:**
- Structured output now included in SearchOutput
- Citations data flows through to conversation API response
- No breaking changes (field is optional, None if not generated)

**Dependencies:**
- Requires PR #626 (Structured Output schema) for StructuredAnswer field definition
- Works with PR #631 (Conversation API config) to enable user-controlled structured output

**Related:**
- Part of Issue #629 fix (citations not displaying)
- Small but critical piece of the structured output pipeline

* fix(search-service): Add structured_answer support to SearchContext and SearchOutput

- Add structured_answer field to SearchOutput schema with StructuredAnswer import
- Add structured_answer field to SearchContext dataclass for pipeline data flow
- Fix quote style in search_service.py debug logging (double quotes)
- Apply Ruff formatting to search_service.py

This ensures structured output with citations generated by generation_stage.py
flows through to the SearchOutput response and reaches the frontend.

Related to PR #626 (Structured Output schema)
Enables PR #630 (Frontend Citations UI)

Signed-off-by: Claude <[email protected]>
Signed-off-by: manavgup <[email protected]>

---------

Signed-off-by: Claude <[email protected]>
Signed-off-by: manavgup <[email protected]>

Author: manavgup

backend/rag_solution/services/search_service.py

@@ -569,6 +569,18 @@ async def _search_with_pipeline(self, search_input: SearchInput) -> SearchOutput
         # Convert cot_output from ChainOfThoughtOutput to dict if present
         cot_output_dict = result_context.cot_output.model_dump() if result_context.cot_output else None
 
+        # Debug: Log document_metadata before creating SearchOutput
+        logger.info(
+            "📊 SEARCH_SERVICE: result_context.document_metadata has %d items", len(result_context.document_metadata)
+        )
+        if result_context.document_metadata:
+            logger.info(
+                "📊 SEARCH_SERVICE: First doc_metadata = %s",
+                result_context.document_metadata[0].document_name
+                if hasattr(result_context.document_metadata[0], "document_name")
+                else "NO DOCUMENT_NAME",
+            )
+
         search_output = SearchOutput(
             answer=cleaned_answer,
             documents=result_context.document_metadata,