T-Watch provisioned via rnodeconf with patched T-Watch product
code (0xEC). Radio online at 868MHz, GPS active.
Key finding: radio SPI takes only 6µs/loop when online and idle
(vs 99ms when stopRadio() was called every loop). Main loop
stable at 289µs. Full frame 83ms (37ms flush + 45ms render).
rnodeconf requires T-Watch product code (0xEC) and model (0xDA)
to be added to the RNS Utilities package. Signing key generated
locally for self-signed provisioning.
