fix(workflows): route reaction invites to Slack live queue

[decofe]

Summary

• route the Slack reaction calendar poller to the isolated Slack-live workflow queue
• route its DM sender to the same queue
• cover both workflow names in the queue-classification test

Validation

• cargo +nightly fmt --package centaur-workflows -- --check
• cargo test -p centaur-workflows scheduled_etls_use_isolated_etl_queues
• cargo +nightly clippy -p centaur-workflows --all-targets -- -D warnings

Prompted by: @letstokenize

[mslipper]

Is this a tempo-specific workflow? If so we should find a better way of configuring this than hardcoding.