fix(radio): drop companion FEM wiring; wire t096 + tracker_v2 FEM overrides

companion_radio has its own NodePrefs without radio_fem_rxgain (matching
upstream, which doesn't wire companion either), so the startup call added in
e905451d broke every companion build:
  MyMesh.cpp:973: error: 'struct NodePrefs' has no member named 'radio_fem_rxgain'
It went unnoticed behind the pre-existing companion build failures.

Also port upstream's FEM LNA overrides for heltec_t096 and heltec_tracker_v2
verbatim (board overrides + isLNAEnabled/const getters), so all three boards
upstream wires now match instead of reporting unsupported. Both variant files
compile; those targets still fail overall on the pre-existing non-observer
MQTT-source build-config issue (unchanged with this work stashed).

examples/companion_radio/MyMesh.cpp

@@ -970,7 +970,8 @@ void MyMesh::begin(bool has_display) {
   radio_driver.setRxBoostedGainMode(_prefs.rx_boosted_gain);
   MESH_DEBUG_PRINTLN("RX Boosted Gain Mode: %s",
                      radio_driver.getRxBoostedGainMode() ? "Enabled" : "Disabled");
-  board.setLoRaFemLnaEnabled(_prefs.radio_fem_rxgain);   // LoRa FEM LNA (FEM boards only)
+  // NOTE: no FEM LNA wiring here — companion has its own NodePrefs without
+  // radio_fem_rxgain, matching upstream (which also doesn't wire companion).
 }
 
 const char *MyMesh::getNodeName() {

variants/heltec_t096/LoRaFEMControl.h

@@ -12,8 +12,9 @@ class LoRaFEMControl
     void setRxModeEnable(void);
     void setRxModeEnableWhenMCUSleep(void);
     void setLNAEnable(bool enabled);
-    bool isLnaCanControl(void) { return lna_can_control; }
+    bool isLnaCanControl(void) const { return lna_can_control; }
     void setLnaCanControl(bool can_control) { lna_can_control = can_control; }
+    bool isLNAEnabled(void) const { return lna_enabled; }
 
   private:
     bool lna_enabled = false;

variants/heltec_t096/T096Board.cpp

@@ -123,4 +123,22 @@ void T096Board::powerOff() {
 
 const char* T096Board::getManufacturerName() const {
   return "Heltec T096";
+}
+
+bool T096Board::setLoRaFemLnaEnabled(bool enable) {
+  if (!loRaFEMControl.isLnaCanControl()) {
+    return false;
+  }
+
+  loRaFEMControl.setLNAEnable(enable);
+  loRaFEMControl.setRxModeEnable();
+  return true;
+}
+
+bool T096Board::canControlLoRaFemLna() const {
+  return loRaFEMControl.isLnaCanControl();
+}
+
+bool T096Board::isLoRaFemLnaEnabled() const {
+  return loRaFEMControl.isLNAEnabled();
 }

variants/heltec_t096/T096Board.h

@@ -25,4 +25,7 @@ public:
   uint16_t getBattMilliVolts() override;
   const char* getManufacturerName() const override ;
   void powerOff() override;
+  bool setLoRaFemLnaEnabled(bool enable) override;
+  bool canControlLoRaFemLna() const override;
+  bool isLoRaFemLnaEnabled() const override;
 };

variants/heltec_tracker_v2/HeltecTrackerV2Board.cpp

@@ -82,3 +82,21 @@ void HeltecTrackerV2Board::begin() {
   const char* HeltecTrackerV2Board::getManufacturerName() const {
     return "Heltec Tracker V2";
   }
+
+  bool HeltecTrackerV2Board::setLoRaFemLnaEnabled(bool enable) {
+    if (!loRaFEMControl.isLnaCanControl()) {
+      return false;
+    }
+
+    loRaFEMControl.setLNAEnable(enable);
+    loRaFEMControl.setRxModeEnable();
+    return true;
+  }
+
+  bool HeltecTrackerV2Board::canControlLoRaFemLna() const {
+    return loRaFEMControl.isLnaCanControl();
+  }
+
+  bool HeltecTrackerV2Board::isLoRaFemLnaEnabled() const {
+    return loRaFEMControl.isLNAEnabled();
+  }

variants/heltec_tracker_v2/HeltecTrackerV2Board.h

@@ -21,5 +21,8 @@ public:
   void powerOff() override;
   uint16_t getBattMilliVolts() override;
   const char* getManufacturerName() const override ;
+  bool setLoRaFemLnaEnabled(bool enable) override;
+  bool canControlLoRaFemLna() const override;
+  bool isLoRaFemLnaEnabled() const override;
 
 };

variants/heltec_tracker_v2/LoRaFEMControl.h

@@ -12,8 +12,9 @@ class LoRaFEMControl
     void setRxModeEnable(void);
     void setRxModeEnableWhenMCUSleep(void);
     void setLNAEnable(bool enabled);
-    bool isLnaCanControl(void) { return lna_can_control; }
+    bool isLnaCanControl(void) const { return lna_can_control; }
     void setLnaCanControl(bool can_control) { lna_can_control = can_control; }
+    bool isLNAEnabled(void) const { return lna_enabled; }
 
   private:
     bool lna_enabled = false;