Add heltec_v4 board. (#7845)

* add heltec_v4 board.

* Update variants/esp32s3/heltec_v4/platformio.ini

Co-authored-by: Austin <vidplace7@gmail.com>

* Limit the maximum output power.

* Trunk fixes

Fixes formatting to match meshtastic trunk linter.

* Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>
Co-authored-by: Austin <vidplace7@gmail.com>
Co-authored-by: Tom Fifield <tom@tomfifield.net>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

boards/heltec_v4.json

@@ -0,0 +1,43 @@
+{
+  "build": {
+    "arduino": {
+      "ldscript": "esp32s3_out.ld",
+      "partitions": "default_16MB.csv",
+      "memory_type": "qio_qspi"
+    },
+    "core": "esp32",
+    "extra_flags": [
+      "-DBOARD_HAS_PSRAM",
+      "-DARDUINO_USB_CDC_ON_BOOT=1",
+      "-DARDUINO_USB_MODE=0",
+      "-DARDUINO_RUNNING_CORE=1",
+      "-DARDUINO_EVENT_RUNNING_CORE=1"
+    ],
+    "f_cpu": "240000000L",
+    "f_flash": "80000000L",
+    "flash_mode": "qio",
+    "psram_type": "qspi",
+    "hwids": [["0x303A", "0x1001"]],
+    "mcu": "esp32s3",
+    "variant": "heltec_v4"
+  },
+  "connectivity": ["wifi", "bluetooth", "lora"],
+  "debug": {
+    "default_tool": "esp-builtin",
+    "onboard_tools": ["esp-builtin"],
+    "openocd_target": "esp32s3.cfg"
+  },
+  "frameworks": ["arduino", "espidf"],
+  "name": "heltec_wifi_lora_32 v4 (16 MB FLASH, 2 MB PSRAM)",
+  "upload": {
+    "flash_size": "16MB",
+    "maximum_ram_size": 2097152,
+    "maximum_size": 16777216,
+    "use_1200bps_touch": true,
+    "wait_for_upload_port": true,
+    "require_upload_port": true,
+    "speed": 921600
+  },
+  "url": "https://heltec.org/",
+  "vendor": "heltec"
+}