feat: add Char Test screen and extend Lemon font to Greek/Cyrillic

- Add CharTestScreen showing sample characters from 11 scripts
  (PL, DE, CS, FR, NO, HU, HR, TR, LT, Cyrillic, Greek) as raw
  UTF-8 to verify native font rendering without transliteration
- Add "Char Test" entry to ToolsScreen menu
- Regenerate LemonFont.h from lemon.bdf with full U+0020–U+04FF
  range: 1074 BDF glyphs + 174 placeholders, 4111 bitmap bytes;
  adds Greek (137 glyphs) and Cyrillic (256 glyphs) coverage;
  also fixes space advance (DWIDTH=5, was BBX+1=1)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

examples/companion_radio/ui-new/CharTestScreen.h

@@ -0,0 +1,69 @@
+#pragma once
+// Test screen that displays sample characters from various alphabets/scripts.
+// Useful for verifying transliteration and font coverage on experimental fonts.
+
+class CharTestScreen : public UIScreen {
+  UITask* _task;
+  int _scroll;
+  int _visible;  // updated each render, used by handleInput
+
+  struct TestLine { const char* label; const char* sample; };
+  static const int LINE_COUNT = 11;
+  static const TestLine LINES[LINE_COUNT];
+
+public:
+  CharTestScreen(UITask* task) : _task(task), _scroll(0), _visible(6) {}
+
+  void enter() { _scroll = 0; }
+
+  int render(DisplayDriver& display) override {
+    display.setTextSize(1);
+    display.setColor(DisplayDriver::LIGHT);
+    display.drawTextCentered(display.width() / 2, 0, "CHAR TEST");
+    display.fillRect(0, 10, display.width(), 1);
+
+    const int lineH  = display.getLineHeight();
+    const int startY = 12;
+    _visible = (display.height() - startY) / lineH;
+
+    for (int i = 0; i < _visible && (_scroll + i) < LINE_COUNT; i++) {
+      char buf[80];
+      snprintf(buf, sizeof(buf), "%s:%s", LINES[_scroll + i].label, LINES[_scroll + i].sample);
+      display.setCursor(2, startY + i * lineH);
+      display.print(buf);
+    }
+
+    if (_scroll > 0) {
+      display.setCursor(display.width() - 6, startY);
+      display.print("^");
+    }
+    if (_scroll + _visible < LINE_COUNT) {
+      display.setCursor(display.width() - 6, display.height() - lineH);
+      display.print("v");
+    }
+    return 500;
+  }
+
+  bool handleInput(char c) override {
+    if (c == KEY_UP   && _scroll > 0)                       { _scroll--; return true; }
+    if (c == KEY_DOWN && _scroll + _visible < LINE_COUNT)   { _scroll++; return true; }
+    if (c == KEY_CANCEL || c == KEY_CONTEXT_MENU) { _task->gotoToolsScreen(); return true; }
+    return false;
+  }
+};
+
+// Sample strings are printed as raw UTF-8 (no transliteration) to test native font coverage.
+// Lemon font covers U+0020–U+04FF: Latin, Greek and Cyrillic all render natively.
+const CharTestScreen::TestLine CharTestScreen::LINES[CharTestScreen::LINE_COUNT] = {
+  { "PL", "ąćęłńóśźżĄĆĘŁŃ"  },  // Polish
+  { "DE", "äöüÄÖÜß"           },  // German
+  { "CS", "čďěňřšťžůýČŘŠŤŽ"  },  // Czech/Slovak
+  { "FR", "àâçèêëîïôùûÿ"      },  // French
+  { "NO", "åæøÅÆØðþÐÞ"        },  // Nordic/Icelandic
+  { "HU", "áéíőúűÁÉÍŐÚŰ"      },  // Hungarian
+  { "HR", "čćđšžČĆĐŠŽ"        },  // Croatian
+  { "TR", "çğışöüİŞĞ"          },  // Turkish
+  { "LT", "āēīūģķļņŗėįų"      },  // Baltic (Latvian/Lithuanian)
+  { "RU", "АБВГДЕЖЗабвгдеж"   },  // Cyrillic (→ blocks █)
+  { "GR", "\xCE\xB1\xCE\xB2\xCE\xB3\xCE\xB4\xCE\xB5\xCE\xB6\xCE\xB7\xCE\xB8\xCE\xB9\xCE\xBA" },  // Greek αβγδεζηθικ (→ blocks █)
+};

examples/companion_radio/ui-new/ToolsScreen.h

@@ -6,7 +6,7 @@ class ToolsScreen : public UIScreen {
   UITask* _task;
   int _sel;
 
-  static const int ITEM_COUNT = 4;
+  static const int ITEM_COUNT = 5;
   static const char* ITEMS[ITEM_COUNT];
 
 public:
@@ -46,8 +46,9 @@ public:
       if (_sel == 1) { _task->gotoBotScreen();        return true; }
       if (_sel == 2) { _task->gotoNearbyScreen();     return true; }
       if (_sel == 3) { _task->gotoAutoAdvertScreen(); return true; }
+      if (_sel == 4) { _task->gotoCharTestScreen();   return true; }
     }
     return false;
   }
 };
-const char* ToolsScreen::ITEMS[4] = { "Ringtone Editor", "Auto-Reply Bot", "Nearby Nodes", "Auto-Advert" };
+const char* ToolsScreen::ITEMS[5] = { "Ringtone Editor", "Auto-Reply Bot", "Nearby Nodes", "Auto-Advert", "Char Test" };

examples/companion_radio/ui-new/UITask.cpp

@@ -127,6 +127,7 @@ static const uint16_t HP_ALL       = 0x01FF;
 #include "NearbyScreen.h"
 #include "DashboardConfigScreen.h"
 #include "AutoAdvertScreen.h"
+#include "CharTestScreen.h"
 #include "ToolsScreen.h"
 
 // ── HomeScreen ────────────────────────────────────────────────────────────────
@@ -808,6 +809,7 @@ void UITask::begin(DisplayDriver* display, SensorManager* sensors, NodePrefs* no
   nearby_screen = new NearbyScreen(this);
   dashboard_config = new DashboardConfigScreen(this, node_prefs);
   auto_advert_screen = new AutoAdvertScreen(this, node_prefs);
+  char_test_screen   = new CharTestScreen(this);
   setCurrScreen(splash);
 
   applyBrightness();
@@ -847,6 +849,11 @@ void UITask::gotoAutoAdvertScreen() {
   setCurrScreen(auto_advert_screen);
 }
 
+void UITask::gotoCharTestScreen() {
+  ((CharTestScreen*)char_test_screen)->enter();
+  setCurrScreen(char_test_screen);
+}
+
 void UITask::playMelody(const char* melody) {
 #ifdef PIN_BUZZER
   buzzer.playForced(melody);

examples/companion_radio/ui-new/UITask.h

@@ -72,6 +72,7 @@ class UITask : public AbstractUITask {
   UIScreen* nearby_screen;
   UIScreen* dashboard_config;
   UIScreen* auto_advert_screen;
+  UIScreen* char_test_screen;
   UIScreen* curr;
 
   void userLedHandler();
@@ -113,6 +114,7 @@ public:
   void gotoNearbyScreen();
   void gotoDashboardConfig();
   void gotoAutoAdvertScreen();
+  void gotoCharTestScreen();
   void playMelody(const char* melody);
   void stopMelody();
   bool isMelodyPlaying();