refactor(ui): upstream's UIColor palette in place of the DARK/LIGHT enum

- DisplayDriver takes ColorVal; each driver's .cpp defines the UIColor roles
  (window_bkg, primary_txt, ...) in its own values. ui-new draws in two:
  window_bkg and primary_txt. OLED and e-ink look as before (sim screens
  pixel-identical).
- E213, E290, LGFX, Null, ST7735, ST7789LCD, U8g2 taken whole from upstream
  (with them the rewritten ST7735 driver and the Heltec V4 R8 TFT display).
- SH1106, SSD1306, ST7789, EinkGfxDisplay and the sim drivers converted.
- ui-orig, ui-tiny, simple_* get upstream's colour roles; the repeater's UI
  taken from upstream (its power-off screen).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

examples/companion_radio/ui-new/BotScreen.h

@@ -84,7 +84,7 @@ public:
 
   int render(DisplayDriver& display) override {
     display.setTextSize(1);
-    display.setColor(DisplayDriver::LIGHT);
+    display.setColor(UIColor::primary_txt);
 
     if (_kb_row >= 0) {
       return _kb->render(display);
@@ -103,7 +103,7 @@ public:
     if (sent > 0) {
       display.setCursor(display.width() - cw - 1, 0);
       display.print(cbuf);
-      display.setColor(DisplayDriver::LIGHT);
+      display.setColor(UIColor::primary_txt);
     }
 
     int n = botcfg::rowCount(_tab);
@@ -138,7 +138,7 @@ public:
       }
       int mqr = info::listRow(display, y, r.label, shown, sel, reserve);
       if (mqr > 0) mq_delay = mqr;
-      display.setColor(DisplayDriver::LIGHT);
+      display.setColor(UIColor::primary_txt);
     });
     return 2000;
   }