Add CXT Studio 12E3 keyboard (#24749)

Co-authored-by: jack <jack@pngu.org>
Co-authored-by: Joel Challis <git@zvecr.com>

keyboards/cxt_studio/12e3/keymaps/default/keymap.c

@@ -0,0 +1,40 @@
+// Copyright 2023 QMK
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include QMK_KEYBOARD_H
+
+enum my_layers {
+    _BASE,
+    _RGBL,
+};
+
+const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
+
+    [_BASE] = LAYOUT(
+        KC_PSCR, KC_CUT, KC_COPY, KC_PSTE,  MS_BTN3, RM_TOGG,
+        KC_CALC, KC_UNDO, KC_MPLY, KC_MNXT,     KC_MUTE,
+        MO(1), KC_LGUI, KC_DEL, KC_APP
+    ),
+
+    [_RGBL] = LAYOUT(
+        RM_NEXT, RM_SATU, KC_INS, KC_DEL,   _______, _______,
+        RM_PREV, RM_SATD, KC_PGUP, KC_HOME,     _______,
+        _______, QK_BOOT, KC_PGDN, KC_END
+    ),
+};
+
+#if defined(ENCODER_MAP_ENABLE)
+const uint16_t PROGMEM encoder_map[][NUM_ENCODERS][NUM_DIRECTIONS] = {
+    // Encoders: Left, Right, Big
+    [_BASE] = {
+        ENCODER_CCW_CW(MS_WHLD, MS_WHLU),
+        ENCODER_CCW_CW(KC_PGDN, KC_PGUP),
+        ENCODER_CCW_CW(KC_VOLD, KC_VOLU)
+    },
+    [_RGBL] = {
+        ENCODER_CCW_CW(RM_HUED, RM_HUEU),
+        ENCODER_CCW_CW(RM_SPDD, RM_SPDU),
+        ENCODER_CCW_CW(RM_VALD, RM_VALU)
+    },
+};
+#endif