Always-on station mode burns ~410 mAh/day on the radio alone; on-demand
drops that to ~25 mAh/day at 10 Publishes/day. Radio comes up on Ctrl-G
with a 10 s association timeout, holds for a ~90 s grace window after
each Publish, then tears down. SNTP cached up to 24 h to avoid
re-querying every Publish.
Also removes stale SoftAP provisioning bullets that contradicted the
"v0.1 has no provisioning module" stance later in the same doc.
d5f22c697c