docs(webapp): clarify Sentry trace_id override is intentional

Adds a code comment on addOtelTraceContextToEvent explaining that
overwriting Sentry's contexts.trace.trace_id is the design intent —
with skipOpenTelemetrySetup: true, Sentry's auto-generated trace_id
is unrelated to OTel, and replacing it is the whole point of the
processor.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: d-cs

apps/webapp/sentry.server.ts

@@ -22,6 +22,11 @@ export function getActiveTraceIds():
 export function addOtelTraceContextToEvent(event: Event, _hint: EventHint): Event {
   const ids = getActiveTraceIds();
   if (!ids) return event;
+  // We intentionally overwrite Sentry's own trace_id/span_id on contexts.trace.
+  // With skipOpenTelemetrySetup: true, Sentry generates an internal trace_id
+  // unrelated to OTel; replacing it with the active OTel ids is the whole
+  // point of this processor — it makes Sentry issues navigable to the
+  // corresponding OTel trace in any backend.
   return {
     ...event,
     contexts: {