fix: enable radio.rxgain CLI command for LR1110 (T1000-E)

USE_LR1110 was missing from the preprocessor guard in CommonCLI.cpp,
causing both get and set to fail silently on T1000-E:

- get radio.rxgain returned the full radio config string (fell through
  to the memcmp("radio", 5) branch)
- set radio.rxgain returned "unknown config" (no branch matched)

Fix: add -D USE_LR1110 to variants/t1000-e/platformio.ini and include
USE_LR1110 in the #if guard on both get and set branches.

CustomLR1110Wrapper already implements setRxBoostedGainMode() and
getRxBoostedGainMode() via the RadioLibWrapper virtual interface,
so no radio-layer changes are required.

Tested on T1000-E: get/set/persist all confirmed working.

variants/t1000-e/platformio.ini

@@ -13,6 +13,7 @@ build_flags = ${nrf52_base.build_flags}
   -D USER_BTN_PRESSED=HIGH
   -D PIN_STATUS_LED=24
   -D RADIO_CLASS=CustomLR1110
+  -D USE_LR1110
   -D WRAPPER_CLASS=CustomLR1110Wrapper
   -D LORA_TX_POWER=22
   -D RF_SWITCH_TABLE