shields: add two shield definitions for modulino boards

Add two shield definitions for the the modulino buttons and smartleds
modules.

Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>

boards/shields/arduino_modulino_buttons/Kconfig.shield

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+# Copyright 2025 Google LLC
+# SPDX-License-Identifier: Apache-2.0
+
+config SHIELD_ARDUINO_MODULINO_BUTTONS
+	def_bool $(shields_list_contains,arduino_modulino_buttons)

boards/shields/arduino_modulino_buttons/arduino_modulino_buttons.overlay

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+/*
+ * Copyright 2025 Google LLC
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/dt-bindings/input/input-event-codes.h>
+#include <zephyr/dt-bindings/led/led.h>
+
+&qwiic_i2c {
+	modulino-buttons@3e {
+		compatible = "i2c-device";
+		reg = <0x3e>;
+
+		modulino_buttons: modulino-buttons {
+			compatible = "arduino,modulino-buttons";
+			zephyr,codes = <INPUT_KEY_A>,
+				       <INPUT_KEY_B>,
+				       <INPUT_KEY_C>;
+		};
+
+		modulino_leds: modulino-leds {
+			compatible = "arduino,modulino-buttons-leds";
+		};
+	};
+
+};

boards/shields/arduino_modulino_buttons/doc/index.rst

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+.. _arduino_modulino_buttons:
+
+Arduino Modulino Buttons
+########################
+
+Overview
+********
+
+The Arduino Modulino Buttons is a QWIIC compatible module with three buttons
+and three LEDs.
+
+
+.. image:: img/arduino_modulino_buttons.webp
+     :align: center
+     :alt: Arduino Modulino Buttons module
+
+Programming
+***********
+
+Set ``--shield arduino_modulino_buttons`` when you invoke ``west build``, the
+buttons will be available through the input subsystem and the LEDs through the
+LED subsystem.
+
+For example,
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/subsys/input
+   :board: arduino_uno_r4@wifi
+   :shield: arduino_modulino_buttons
+   :goals: build

boards/shields/arduino_modulino_smartleds/Kconfig.shield

@@ -0,0 +1,5 @@
+# Copyright 2025 Google LLC
+# SPDX-License-Identifier: Apache-2.0
+
+config SHIELD_ARDUINO_MODULINO_SMARTLEDS
+	def_bool $(shields_list_contains,arduino_modulino_smartleds)

boards/shields/arduino_modulino_smartleds/arduino_modulino_smartleds.overlay

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+/*
+ * Copyright 2025 Google LLC
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/dt-bindings/led/led.h>
+
+/ {
+	aliases {
+		led-strip = &modulino_smartleds;
+	};
+};
+
+&qwiic_i2c {
+	modulino_smartleds: modulino-smartleds@36 {
+		compatible = "arduino,modulino-smartleds";
+		reg = <0x36>;
+		chain-length = <8>;
+		color-mapping = <LED_COLOR_ID_RED
+				 LED_COLOR_ID_GREEN
+				 LED_COLOR_ID_BLUE>;
+	};
+};

boards/shields/arduino_modulino_smartleds/doc/index.rst

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+.. _arduino_modulino_smartleds:
+
+Arduino Modulino smart LEDs
+###########################
+
+Overview
+********
+
+The Arduino Modulino smart LEDs is a QWIIC compatible module with 8 addressable
+LEDs.
+
+
+.. image:: img/arduino_modulino_smartleds.webp
+     :align: center
+     :alt: Arduino Modulino Smart LEDs
+
+Programming
+***********
+
+Set ``--shield arduino_modulino_smartleds`` when you invoke ``west build``, the
+leds will be available through the LED strip subsystem.
+
+For example,
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/drivers/led/led_strip
+   :board: arduino_uno_r4@wifi
+   :shield: arduino_modulino_smartleds
+   :goals: build