Admin Run Digest Deliver

Manually trigger the Market Digest deliver phase (the Monday email).

Same code path as python -m app.cron.digest_deliver. Sends each entitled profile's digest of confirmed watchlist artists; profiles with nothing confirmed get no email; once-only per artist via digest_runs delivered_ids. Returns the run summary so you can smoke-test in dev/prod without waiting for the cron tick.

Honors DIGEST_DELIVER_TEST_PROFILE (single-profile run, bypasses the entitlement gate), DIGEST_DELIVER_TEST_RECIPIENT (reroute all email + skip the once-only recording), and DIGEST_DRY_RUN (render, send nothing).