I2S driver implementation (#480)

* **New Features**
  * ESP32 I2S controller support: runtime-configurable digital audio I/O with read/write/set/get operations and multiple formats.

* **Board Support**
  * LilyGO T-Deck device tree entry added to enable I2S peripheral pin configuration.

* **Documentation**
  * New/updated bindings and descriptors for I2S, I2C, GPIO, and root nodes.

* **Other**
  * Added GPIO "no pin" sentinel and exposed I2S controller API symbols.

Platforms/PlatformEsp32/Include/tactility/bindings/esp32_i2s.h

@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: Apache-2.0
+#pragma once
+
+#include <tactility/bindings/bindings.h>
+#include <tactility/drivers/esp32_i2s.h>
+#include <driver/i2s_common.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+DEFINE_DEVICETREE(esp32_i2s, struct Esp32I2sConfig)
+
+#ifdef __cplusplus
+}
+#endif

Platforms/PlatformEsp32/Include/tactility/drivers/esp32_i2s.h

@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: Apache-2.0
+#pragma once
+
+#include <tactility/drivers/i2s_controller.h>
+#include <driver/i2s_common.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct Esp32I2sConfig {
+    i2s_port_t port;
+    int pin_bclk;
+    int pin_ws;
+    int pin_data_out;
+    int pin_data_in;
+    int pin_mclk;
+};
+
+#ifdef __cplusplus
+}
+#endif