Keep trace summaries from breaking Logs and fix their counts

A failed trace-summary lookup now leaves the Logs page intact without
chips. Tool-call counts include only calls that ran, not their paused,
denied or skipped records. A local guardrail that fires unchanged on every
streamed segment is recorded once, so it cannot use up the span cap.

docsgpt/tracing/__init__.py

@@ -43,6 +43,7 @@ from docsgpt.tracing.core import (
     bind,
     bind_if_unset,
     current_trace,
+    first_occurrence,
     mark_content_blocked,
     span,
     start_span,
@@ -78,6 +79,7 @@ __all__ = [
     "bind_if_unset",
     "current_trace",
     "discard",
+    "first_occurrence",
     "flush",
     "mark_content_blocked",
     "span",