fix(api): configure root_path for OpenAPI docs behind reverse proxy

Add ROOT_PATH environment variable support so FastAPI generates correct
URLs for Swagger UI when served behind nginx at /api. This fixes the
"invalid version field" error when accessing /api/docs.

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

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

SPARC/api.py

@@ -161,6 +161,7 @@ app = FastAPI(
     description="Semiconductor Patent & Analytics Report Core - Patent portfolio analysis using AI",
     version="1.0.0",
     lifespan=lifespan,
+    root_path=config.root_path,
 )
 
 # Add CORS middleware for React frontend