Add WidgetCharset class for character selection

with cycling through charset and callback handling.

- Introduces WidgetCharset class inheriting BaseWidgetValue<char>.
- Allows user to select characters from a specified charset.
- Implements methods for cycling through characters, clearing value, and triggering callbacks.

src/ItemWidget.h

@@ -26,7 +26,6 @@ struct make_index_sequence<0, Is...> {
     using type = index_sequence<Is...>;
 };
 
-// Updated ItemWidget class supporting zero or more widgets
 template <typename... Ts>
 class ItemWidget : public BaseItemManyWidgets {
   public:

src/widget/WidgetCharset.h

@@ -0,0 +1,106 @@
+// Creator: @ShishkinDmitriy
+#pragma once
+
+#include "BaseWidgetValue.h"
+
+/**
+ * @class WidgetCharset
+ * @brief Widget that allows user to select a character from a charset.
+ * Manages a character value within a specified charset, allowing cycling through characters.
+ */
+class WidgetCharset : public BaseWidgetValue<char> {
+    friend class ItemCharsetWidgets;
+
+  protected:
+    const char*& charset;
+    const bool cycle;
+    uint8_t charsetPosition = 0;
+
+  public:
+    WidgetCharset(
+        const char value,
+        const char*& charset,
+        const char* format,
+        const uint8_t cursorOffset,
+        const bool cycle,
+        void (*callback)(char))
+        : BaseWidgetValue<char>(value, format, cursorOffset, callback), charset(charset), cycle(cycle) {}
+
+  protected:
+    uint8_t draw(char* buffer, const uint8_t start) override {
+        if (start >= ITEM_DRAW_BUFFER_SIZE) return 0;
+        return snprintf(buffer + start, ITEM_DRAW_BUFFER_SIZE - start, format, value == '\0' ? ' ' : value);
+    }
+
+    /**
+     * @brief Process command.
+     *
+     * Handle commands:
+     * - `UP` - go to the next character in the charset and trigger callback
+     * - `DOWN` - go to the previous character in the charset and trigger callback
+     * - `BACKSPACE` - clear the value
+     */
+    bool process(LcdMenu* menu, const unsigned char command) override {
+        MenuRenderer* renderer = menu->getRenderer();
+        if (renderer->isInEditMode()) {
+            switch (command) {
+                case UP:
+                    if (nextChar()) {
+                        value = charset[charsetPosition];
+                        BaseWidgetValue<char>::handleChange();
+                        printLog(F("WidgetCharset::nextChar"), value);
+                    }
+                    return true;
+                case DOWN:
+                    if (previousChar()) {
+                        value = charset[charsetPosition];
+                        BaseWidgetValue<char>::handleChange();
+                        printLog(F("WidgetCharset::previousChar"), value);
+                    }
+                    return true;
+                case BACKSPACE:
+                    if (backspace()) {
+                        printLog(F("WidgetCharset::backspace"));
+                        BaseWidgetValue<char>::handleChange();
+                    }
+                    return true;
+                default:
+                    return false;
+            }
+        }
+        return false;
+    }
+
+    bool backspace() {
+        if (value != '\0') {
+            value = '\0';
+            charsetPosition = 0;
+            return true;
+        }
+        return false;
+    }
+
+    bool nextChar() {
+        if (charset[charsetPosition + 1] != '\0') {
+            charsetPosition++;
+            return true;
+        }
+        if (cycle) {
+            charsetPosition = 0;
+            return true;
+        }
+        return false;
+    }
+
+    bool previousChar() {
+        if (charsetPosition > 0) {
+            charsetPosition--;
+            return true;
+        }
+        if (cycle) {
+            charsetPosition = strlen(charset) - 1;
+            return true;
+        }
+        return false;
+    }
+};