doc: clarify sqlite.db.query as profiling event

Author: araujogui

doc/api/diagnostics_channel.md

@@ -1928,12 +1928,20 @@ added: REPLACEME
   instead.
 * `database` {DatabaseSync} The [`DatabaseSync`][] instance that executed the
   statement.
-* `duration` {number} The estimated statement run time in nanoseconds.
-
-Emitted when a SQL statement is executed against a [`DatabaseSync`][] instance.
-This allows subscribers to observe every SQL statement executed without
-modifying the database code itself. Tracing is zero-cost when there are no
-subscribers.
+* `duration` {number} SQLite's internal estimate of the statement run time in
+  nanoseconds. This reflects C-layer execution time only and does not include
+  JavaScript binding overhead such as argument marshaling or result-row
+  construction.
+
+Emitted after a SQL statement finishes executing against a [`DatabaseSync`][]
+instance. This is a **profiling** event: it fires once per statement upon
+completion and reports an estimated duration from SQLite's internal profiler.
+It is not a distributed-tracing span. There is no corresponding start event,
+no async context propagation, and no parent-span linkage. If you need
+OpenTelemetry-compatible spans or async context propagation, wrap your SQLite
+calls with a [`TracingChannel`][] at the JavaScript layer instead.
+
+Publishing is zero-overhead when there are no subscribers.
 
 [BoundedChannel Channels]: #boundedchannel-channels
 [TracingChannel Channels]: #tracingchannel-channels