feat(cli): make promote status inspect campaign snapshots

[aiirvizionz]

Closes #890

This refreshes the promote status implementation against the latest master while retaining the existing campaign stop command.

Changes:

• add a read-only promote status report sourced from .sh1pt/campaigns.json
• support platform filtering, JSON output, and an explicit snapshot path
• preserve the promote stop selection and dry-run behavior
• keep malformed or missing snapshots as actionable, non-networked states

Validation:

• packages/cli/src/commands/promote.test.ts: 26 tests passed
• no credentials or network calls are required for status aggregation

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.