Append tool invocations to a call

Attach tool invocations that fired during a call to an already-existing call, asynchronously after the call was created. Use this when the tool-call data becomes available later than the call itself (e.g. a Roark simulation, or a call submitted via POST /v1/call before its tools were ready). Writes are idempotent: re-sending an invocation already present on the call (same tool name and timing) is skipped, so retries converge instead of double-counting. Optionally pass metrics to (re)score metrics over the newly attached tools, which triggers a billed metric collection job and requires the metric:create permission.