The 3-min 64KB video download ran on a timer regardless of whether
anyone was using the app — wasteful upstream bandwidth, and pure churn
while the CDN 403s our IP. Now: no fetch while no stream has been
requested in 15 min (api_stream bumps _LAST_PLAY), and 30-min retry
while DEGRADED. Pill state goes stale while idle, which is fine — the
next viewer's own request is the true signal, and the probe resumes
within a minute of it.