Workers Automatic Tracing: span name only shows HTTP method, not route pattern (e.g. `GET` instead of `GET /foo/{id}`)

Follow-up from discussion [#11062](https://github.com/cloudflare/workers-sdk/discussions/11062#discussioncomment-15755276).

**Current behavior:** The span name / `resource` attribute for incoming request spans is just the HTTP method (e.g. `GET`).

**Expected behavior:** The span name should include the route/endpoint pattern, e.g. `GET /foo/{id}`, similar to how most HTTP server instrumentations name root spans (`{method} {route}` per OTel semantic conventions).

Without the route pattern, APM tools (reported independently for Datadog and Kibana in the linked discussion) can't group/aggregate spans by endpoint — every request under a given method collapses into a single span name regardless of which route handled it.

cc @jmorrell-cloudflare @nevikashah (from the linked discussion)