Fixes and new apps (#30)

- M5 Unit Modules library + M5 Unit Test app
- Minor fixes for TodoList, TwoEleven, Snake, Brainfuck and Breakout
- Fixed SerialConsole to use the uart controller as it was broken in one of the many updates
- Fixed keyboard input in TwoEleven, Breakout, Magic8Ball and Snake
- Bluetooth Media Keys app, supports pressing physical keys to trigger the corresponding buttonmatrix button
- Epub Reader app

Libraries/M5UnitModules/Include/UnitDualButton.h

@@ -0,0 +1,60 @@
+/*
+ * UnitDualButton.h - M5Stack Dual Button Unit (GPIO, Port B)
+ *
+ * Two independent momentary push buttons connected to GPIO pins.
+ * Buttons are active-low - pressing pulls the pin to GND.
+ * Internal pull-up resistors are enabled by the driver.
+ *
+ * Typical Port B pin assignment (M5Stack Core2):
+ *   Button A (red)  - GPIO 36
+ *   Button B (blue) - GPIO 26
+ *
+ * Usage:
+ *   UnitDualButton btn;
+ *   Device* gpioCtrl = device_find_by_name("gpio0");
+ *   if (btn.begin(gpioCtrl, 36, 26)) {
+ *       bool a = btn.isButtonAPressed();
+ *       bool b = btn.isButtonBPressed();
+ *   }
+ *   // When done: btn.end() or let destructor release pins
+ */
+#pragma once
+
+#include <tactility/device.h>
+#include <tactility/drivers/gpio_controller.h>
+#include <cstdint>
+
+class UnitDualButton {
+public:
+    ~UnitDualButton();
+
+    UnitDualButton() = default;
+    UnitDualButton(const UnitDualButton&) = delete;
+    UnitDualButton& operator=(const UnitDualButton&) = delete;
+    UnitDualButton(UnitDualButton&&) = delete;
+    UnitDualButton& operator=(UnitDualButton&&) = delete;
+
+    // Pass a GPIO controller device
+    // Acquire and configure both GPIO pins as inputs with pull-up.
+    // controller: GPIO controller device (e.g. device_find_by_name("gpio0"))
+    // pinA / pinB: physical GPIO pin numbers
+    bool begin(Device* controller, gpio_pin_t pinA, gpio_pin_t pinB);
+
+    // Release GPIO descriptors. Safe to call multiple times.
+    void end();
+
+    bool isPresent() const { return ready_; }
+
+    // True when button A is pressed (active-low: pin reads low).
+    bool isButtonAPressed() const;
+
+    // True when button B is pressed (active-low: pin reads low).
+    bool isButtonBPressed() const;
+
+private:
+    GpioDescriptor* descA_ = nullptr;
+    GpioDescriptor* descB_ = nullptr;
+    bool ready_ = false;
+
+    static bool readPin(GpioDescriptor* desc);
+};