The PUT handler looped forever on HTTPD_SOCK_ERR_TIMEOUT, wedging the
single httpd worker when a push was cut off mid-transfer. Bound it to a
few idle waits and drop truncated files so they never block a re-push.
Receive into a 16 KB heap buffer with a matching stdio buffer. Register
with Tower last (after the first weather TLS fetch) so the content push
it triggers does not contend for memory at boot.
Clément Saillant
d4b7700270