docs(enterprise): consolidate Datadog and structured logs into single guide

Merges the standalone structured_logs guide into a dedicated Datadog
Integration page. The stdout JSON schema is Datadog-Agent-path-specific
in practice (OTLP path uses OpenTelemetry attribute names), so a
vendor-neutral structured-logs page was misleading. Now Datadog customers
have one canonical page covering both ingestion paths plus the dashboard
import, and non-Datadog customers land on the OpenTelemetry Export page
without being buried in Datadog content.

- Delete docs/edge/en/enterprise/guides/structured_logs.mdx; the schema
  reference moves verbatim into the new datadog.mdx as an anchor-linkable
  section.

- Rename datadog_dashboard.mdx to datadog.mdx (preserved via git mv).
  New structure: choose-a-path tabs (Datadog Agent recommended /
  Datadog OTLP intake) → log schema reference (with explicit Info
  callout that it's the Agent-path schema, not OTLP) → dashboard
  import → verify ingestion → customize → troubleshooting.

- Move the Datadog OTLP UI walkthrough (site domain, API key,
  /v1/traces vs /v1/logs paths) onto the Datadog page so it lives in
  exactly one place. Datadog dashboard JSON artifact path stays at
  datadog_dashboard.json — the file name is artifact-specific.

- Reframe capture_telemetry_logs.mdx: add a lead Tip recommending OTel
  as the vendor-neutral first option, and shrink the Datadog tab to a
  pointer to the new Datadog Integration guide.

- Update docs/docs.json en edge sidebar: drop structured_logs, replace
  datadog_dashboard with datadog.

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/docs.json

@@ -515,8 +515,7 @@
                       "edge/en/enterprise/guides/update-crew",
                       "edge/en/enterprise/guides/enable-crew-studio",
                       "edge/en/enterprise/guides/capture_telemetry_logs",
-                      "edge/en/enterprise/guides/structured_logs",
-                      "edge/en/enterprise/guides/datadog_dashboard",
+                      "edge/en/enterprise/guides/datadog",
                       "edge/en/enterprise/guides/azure-openai-setup",
                       "edge/en/enterprise/guides/vertex-ai-workload-identity-setup",
                       "edge/en/enterprise/guides/tool-repository",