fix(text): resolve missing Span import for structured output

- Add lazy import function for Span class to handle runtime usage
- Fix NameError in multi-chunk structured output processing
- Maintain TYPE_CHECKING imports for development experience
- All benchmark tests now passing including structured output
- Resolves issue where Span was only available during type checking

Author: sidmohan0

datafog/services/text_service.py

@@ -10,6 +10,19 @@
 
 if TYPE_CHECKING:
     from datafog.processing.text_processing.regex_annotator.regex_annotator import Span
+else:
+    # Runtime import for Span when needed
+    Span = None
+
+
+def _get_span_class():
+    """Lazily import Span class when needed."""
+    global Span
+    if Span is None:
+        from datafog.processing.text_processing.regex_annotator.regex_annotator import (
+            Span,
+        )
+    return Span
 
 
 class TextService:
@@ -172,7 +185,8 @@ def annotate_text_sync(
                     chunk_spans = self.annotate_text_sync(chunk, structured=True)
                     # Adjust span positions to account for chunk offset
                     for span in chunk_spans:
-                        adjusted_span = Span(
+                        SpanClass = _get_span_class()
+                        adjusted_span = SpanClass(
                             start=span.start + current_offset,
                             end=span.end + current_offset,
                             text=span.text,