feat(techo-lite): add Non-Shell companion BLE variant

[jirogit]

Note on T-Echo Lite variants

LilyGO sells three distinct T-Echo Lite variants:

• T-Echo Lite — full version with 1.22" ePaper display
• T-Echo Lite Non-Shell — USB + Qwiic, no ePaper display, no enclosure
• T-Echo Lite Core — minimal castellated module, no USB, no display

This PR adds a firmware env for the Non-Shell variant.
The Core variant may require a separate env due to different hardware
(no USB interface).

Problem

T-Echo Lite Non-Shell (screenless) users cannot connect via BLE.
The existing companion BLE env inherits DISPLAY_CLASS=GxEPDDisplay
from the base env. This causes display.begin() to run on
non-existent hardware, corrupting BLE initialization.

The result: a random PIN is generated with no way to display it,
making BLE connection impossible.

Note: Issue #1183 and PR #2287 involve related hardware (screenless
T-Echo Lite variants), but address different bugs (battery voltage).
This PR focuses solely on the BLE initialization issue.

Fix

Add LilyGo_T-Echo-Lite_non_shell_companion_radio_ble env:

• excludes DISPLAY_CLASS and ePaper-related build flags
• removes GxEPDDisplay.cpp and ui-new from build sources
• uses static BLE_PIN_CODE=123456

Also fix boards/t-echo.json:

• add nrfutil to upload protocols list
• add use_1200bps_touch=true and wait_for_upload_port=true

Testing

Tested on T-Echo Lite Non-Shell hardware:

• BLE advertises correctly after flashing
• MeshCore app connects successfully via BLE with PIN 123456
• Upload via PlatformIO Upload button works (nrfutil + 1200bps touch)

DFU mode (UF2 flashing) for T-Echo Lite Non-Shell

1. Press and hold RESET button (BLUE LED may or may not flash)
2. Release RESET
3. Quickly press and release RESET again
4. A USB drive appears — copy the .uf2 file onto it

Note: BLUE LED flash may not occur on all units, but the drive
still appears and UF2 flashing works correctly.

Related to #1183, #2287