feat: add schedule list-matching-times command

[chaptersix]

Summary

The Temporal API exposes a ListScheduleMatchingTimes RPC that returns the timestamps a schedule would fire within a given time range. The CLI does not currently have a command for this operation.

Proposed command

temporal schedule list-matching-times \
  --schedule-id <id> \
  --start-time <timestamp> \
  --end-time <timestamp>

This would call ListScheduleMatchingTimes and print the returned timestamps (one per line in text mode, array in JSON mode).

API reference

The RPC is defined in temporalio/api:

• Service definition (RPC): temporal/api/workflowservice/v1/service.proto#L815
• Request/response messages: temporal/api/workflowservice/v1/request_response.proto#L1454-L1468

The request takes namespace, schedule_id, start_time, and end_time. The response is a repeated list of google.protobuf.Timestamp.

[chaptersix]

Relative time values for --start-time and --end-time would also be useful (e.g. now+2h, now-1d) so you don't have to compute absolute timestamps manually. Like should be separate flags.