feat: integrate tracing throughout request pipeline

Instrument the full request flow with trace spans for debugging:

- Wrap expert delegations (librarian/biographer/housekeeper) in spans
- Add orchestrate and synthesize spans to TatlockAgent
- Trace Steward analysis in preprocessing
- Start/end traces in response service with context management
- Simplify router by moving context handling to service layer
- Include tracing router in debug mode
- Remove benchmark recording from tool_tracking and steward service

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/main.py

@@ -23,6 +23,7 @@ from src.core.exceptions import AppException
 from src.core.logging_config import get_logger
 from src.core.router import router as core_router
 from src.core.startup import initialize_application
+from src.core.tracing_router import router as tracing_router
 from src.models.router import router as models_router
 from src.responses.router import router as responses_router
 
@@ -45,7 +46,7 @@ async def lifespan(app: FastAPI) -> AsyncGenerator[None, None]:
         environment=config.ENVIRONMENT.value,
         ollama_host=str(config.OLLAMA_HOST),
         ollama_model=config.OLLAMA_DEFAULT_MODEL,
-        redis_url=config.redis_url,
+        redis_url=config.redis_memory_url,
         log_format=config.log_format,
     )
 
@@ -90,7 +91,12 @@ def create_application() -> FastAPI:
     application.include_router(chat_router, prefix=config.API_PREFIX)
     application.include_router(models_router, prefix=config.API_PREFIX)
     application.include_router(responses_router, prefix=config.API_PREFIX)  # Responses API
-    
+
+    # Conditionally include tracing router (only in debug mode)
+    if config.DEBUG:
+        application.include_router(tracing_router)
+        logger.info("tracing_router_enabled")
+
     return application