- scope the serial config CLI to RP2040; it was exposing the rescue CLI
(cat/rm/erase) on every ESP32 WiFi build, which gates it behind a
physical long-press
- bound and space out RP2040 rejoins: the core's join busy-waits, so cap
it at 5s and retry every 30s instead of every 10s
- stamp the reconnect timer in setup(), so the first loop() doesn't tear
down an association that is still finishing DHCP
- treat stored credentials as a pair, and pass NULL (not "") for an open
network
- teach build_as_lib.py where SerialWifiInterface moved
Michael Graff