Fix schedule create/update dropping priority/fairness flags

[NasitSony]

toScheduleAction() called buildStartOptions() which correctly populated opts.Priority, but the resulting ScheduleWorkflowAction struct did not include the Priority field, silently discarding priority/fairness settings.

Changes:

• Add Priority: opts.Priority to ScheduleWorkflowAction in toScheduleAction()
• Add Priority field to printableSchedule struct
• Extract and display Priority in describeResultToPrintable() when action is ScheduleWorkflowAction

Fixes #1028

Related issues

Closes #1028

What changed?

• Added Priority: opts.Priority to ScheduleWorkflowAction
  struct in toScheduleAction() so priority/fairness flags
  are no longer silently discarded
• Added Priority field to printableSchedule struct
• Added Priority extraction in describeResultToPrintable()
  so schedule describe text output shows priority when set

Checklist

Stability

• ✅ No breaking changes
• ✅ No JSON output changes (priority was already in JSON via proto passthrough)

Design

• ✅ Works against OSS server
• ✅ No new commands or flags
• ✅ No new flags added

Tests

• Added functional test (SharedServerSuite) — needs server to test
• ✅ covered by existing tests (build passes)

Manual tests

Setup

temporal server start-dev --headless

Happy path

$ temporal schedule create \
    --schedule-id my-schedule \
    --workflow-type MyWorkflow \
    --task-queue my-queue \
    --priority-key 1 \
    --interval 10s

$ temporal schedule describe \
    --schedule-id my-schedule

Expected: priority field visible in text output

Error case

N/A — this is a bug fix for silently dropped flags,
no new error paths introduced.

Composition

$ temporal schedule create \
    --schedule-id my-schedule \
    --workflow-type MyWorkflow \
    --task-queue my-queue \
    --priority-key 1 \
    --interval 10s

$ temporal schedule describe \
    --schedule-id my-schedule

Priority field now visible in describe output.