v0.2.0 — read-only dashboards and monitors

Added

• ddog dashboards get <id> / ddog dashboards list [--query] — read dashboard definitions (incl. widget queries).
• ddog monitors list [--name|--tag|--monitor-tag] / ddog monitors get <id> — read monitors and their overall_state.

Both are read-only, over Datadog's v1 API, reusing the same auth/config/output flags as ddog logs.