feat(boards): add M5Stack Cardputer ADV and LilyGO T-Echo Lite KeyShield

New M5Stack Cardputer ADV variant (ESP32-S3, ST7789 TFT, built-in TCA8418
QWERTY keyboard, PI4IOE5V6408 LoRa-cap IO-expander autodetect), and a
KeyShield accessory variant for the existing LilyGO T-Echo Lite (external
TCA8418 T9 keypad + AW21009 backlight driver). Both keyboards share one
ENV_USE_TCA8418 polling block in UITask.cpp::loop(), coexisting with the
unrelated CardKB support (different chip/address/flag).

Fixes carried in from the contributed T-Echo Lite code: swapped GPS RX/TX
pins, TX-LED hooks, TCXO voltage, missing GxEPD2_122_T61 panel include.
Fixed during integration: I2C bus was probed for an RTC before Wire.begin()
configured its pins on Cardputer ADV (silent RTC autodetect failure).

Added dedicated *_solo_dual release envs for both boards (auto-picked up by
the solo-firmware release workflow). Gave the T-Echo Lite KeyShield solo
build -Os/-Ofast-unflag like every other nRF52 solo build (was missing,
cut flash usage from 90.7% to 61.4%).

Ported the shared misc-fixed 6x9 font (full Latin/Greek/Cyrillic, opt-in via
OLED_MISC_FIXED_FONT) to ST7789Display for the Cardputer's on-screen
keyboard. ST7789Spi isn't Adafruit_GFX-based like the other single-font
drivers, and this panel's logical->physical scale is non-integer, so glyphs
are re-packed to XBM and blitted through the existing drawXbm(), which
already does correct fractional-scale boundary math, rather than
duplicating that logic.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

lib/GxEPD2-patch/src/GxEPD2_BW.h

@@ -223,6 +223,9 @@
 #if __has_include("it8951/GxEPD2_it103_1872x1404.h")
 #include "it8951/GxEPD2_it103_1872x1404.h"
 #endif
+#if __has_include("epd/GxEPD2_122_T61.h")
+#include "epd/GxEPD2_122_T61.h"
+#endif
 
 template<typename GxEPD2_Type, const uint16_t page_height>
 class GxEPD2_BW : public GxEPD2_GFX_BASE_CLASS