Hold GC1109 PA_POWER during deep sleep for LNA RX wake

The GC1109 FEM needs its VFEM_Ctrl pin held HIGH during deep sleep
to keep the LNA active, enabling proper RX sensitivity for
wake-on-packet. Without this, the LNA is unpowered during sleep
and RX wake sensitivity is degraded by ~17dB.

Release RTC holds in begin() after configuring GPIO registers
(not before) to ensure glitch-free pin transitions on wake.

Trade-off: ~6.5mA additional sleep current for significantly
improved wake-on-packet range.

variants/heltec_tracker_v2/platformio.ini

@@ -17,11 +17,11 @@ build_flags =
   -D P_LORA_SCLK=9
   -D P_LORA_MISO=11
   -D P_LORA_MOSI=10
-  -D P_LORA_PA_POWER=7 ;power en
-  -D P_LORA_PA_EN=4
-  -D P_LORA_PA_TX_EN=46  ;enable tx
-  -D LORA_TX_POWER=10 ;If it is configured as 10 here, the final output will be 22 dbm.
-  -D MAX_LORA_TX_POWER=22 ;Max SX1262 output
+  -D P_LORA_PA_POWER=7   ; VFEM_Ctrl - GC1109 LDO power enable
+  -D P_LORA_PA_EN=4      ; CSD - GC1109 chip enable (HIGH=on)
+  -D P_LORA_PA_TX_EN=46  ; CPS - GC1109 PA mode (HIGH=full PA, LOW=bypass)
+  -D LORA_TX_POWER=10    ; 10dBm + ~11dB GC1109 gain = ~21dBm output
+  -D MAX_LORA_TX_POWER=22 ; Max SX1262 output -> ~28dBm at antenna
   -D SX126X_DIO2_AS_RF_SWITCH=true
   -D SX126X_DIO3_TCXO_VOLTAGE=1.8
   -D SX126X_CURRENT_LIMIT=140