fix(observability): OTel semantic attrs on access log + status on root span

[igoramf]

Summary

• logRequest() was emitting legacy attribute names (method, path, status, duration_ms). Now uses OTel semantic convention names (http.request.method, url.path, http.response.status_code) so tail-worker and direct-POST logs share the same attribute keys — no aliasing needed in dashboards
• deco.http.request root span never received http.status_code, leaving it permanently Unset even for 5xx responses. Now stamps the status after the handler returns, triggering the setAttribute promotion in otelHttpTracer so 5xx spans surface as StatusCode=Error in ClickHouse

Test plan

• After deploy, query ClickHouse otel_logs — request handled logs should have http.request.method, url.path, http.response.status_code instead of method, path, status
• Query otel_traces for deco.http.request spans with SpanAttributes['http.status_code'] = '500' — should now return results with StatusCode=Error

🤖 Generated with Claude Code

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Summary by cubic

Standardized access logs to OpenTelemetry semantic keys and removed duration_ms, and the root deco.http.request span now records http.status_code. Uses @opentelemetry/semantic-conventions constants.

• Bug Fixes
  • Access logs now emit http.request.method, url.path, http.response.status_code (replaces method, path, status). Dropped duration_ms.
  • Root span sets http.status_code after the handler returns, so 5xx spans surface as StatusCode=Error.

^{Written for commit 9473ccf. Summary will update on new commits.}