Implement 'agc' reset for SX126x & LR11x0 chip families (#9705)

* Implement 'agc' reset for SX126x chip family

There's no actual agc on SX126x chips but you can reset the analog
registers by doing a warm sleep & running calibration.

* Address PR comments & implement for LR11x0 too

* calibrate for configured frequency band

* Gate LR11X0_AGC_RESET

src/mesh/RadioLibInterface.h

@@ -19,6 +19,8 @@
 // In addition to the default Rx flags, we need the PREAMBLE_DETECTED flag to detect whether we are actively receiving
 #define MESHTASTIC_RADIOLIB_IRQ_RX_FLAGS (RADIOLIB_IRQ_RX_DEFAULT_FLAGS | (1 << RADIOLIB_IRQ_PREAMBLE_DETECTED))
 
+#define AGC_RESET_INTERVAL_MS (60 * 1000) // 60 seconds
+
 /**
  * We need to override the RadioLib ArduinoHal class to add mutex protection for SPI bus access
  */
@@ -117,6 +119,13 @@ class RadioLibInterface : public RadioInterface, protected concurrency::Notified
      */
     void pollMissedIrqs();
 
+    /**
+     * Reset AGC by power-cycling the analog frontend.
+     * Subclasses override with chip-specific calibration sequences.
+     * Safe to call periodically — skips if currently sending or receiving.
+     */
+    virtual void resetAGC();
+
     /**
      * Debugging counts
      */