Switch default boot mode back to DIRECT with 500 kHz LFSR to broaden jam coverage

Made-with: Cursor

src/main.cpp

@@ -2600,8 +2600,8 @@ void setup() {
   jamPower     = kPowerTable[jamPowerIdx];
   preferences.putInt("jamPowerIdx", (int)jamPowerIdx);
   capHistoryLoad();
-  // Boot policy: CW — unmodulated carrier on both radios at 315 MHz, all TX power at exactly 315 MHz.
-  jamMode = JamMode::CW;
+  // Boot policy: Direct mode — OOK + 500 kHz LFSR, ~100% duty cycle, covers 314–316 MHz and 432–434 MHz.
+  jamMode = JamMode::DIRECT;
   preferences.putUChar("jamMode", (uint8_t)jamMode);
   logLine("[NVS] jam at boot: always ON | jamPower=" + String(jamPower) + " dBm | jam_mode=" +
           String(jamModeToCstr(jamMode)) + " (default on power-up)");