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

Apps/M5UnitTest/main/Source/TestUnitCardKB2.h

@@ -0,0 +1,51 @@
+#pragma once
+#include "TestViewBase.h"
+#include <UnitCardKB2.h>
+#include <UnitPaHub.h>
+
+class TestUnitCardKB2 final : public TestViewBase {
+public:
+    void onStart(lv_obj_t* parent, AppHandle handle, M5UnitTest* app) override;
+    void onStop() override;
+
+private:
+    UnitPaHub   hub_;
+    UnitCardKB2 unit_;
+    lv_timer_t* timer_      = nullptr;
+    bool        usingPaHub_ = false;
+
+    // Connection selection overlay (shown before connecting)
+    lv_obj_t* connectOverlay_ = nullptr;
+
+    // Main content (shown after connecting)
+    lv_obj_t* lblHistory_  = nullptr;
+    char history_[64]       = {};
+    uint8_t histLen_        = 0;
+
+    // Keyboard grid (only built on screens >= 200px wide)
+    struct KeyCell {
+        const char* label;
+        uint8_t     matchChar;   // ASCII to highlight; 0 = not matchable
+        lv_obj_t*   btn = nullptr;
+        lv_obj_t*   lbl = nullptr;
+    };
+    static constexpr int GRID_KEY_COUNT = 52;
+    KeyCell grid_[GRID_KEY_COUNT] = {};
+    int     gridCount_  = 0;
+    lv_obj_t* activeBtn_ = nullptr;
+
+    lv_obj_t* parentRef_   = nullptr;
+    AppHandle handleRef_   = nullptr;
+
+    void showConnectOverlay();
+    void connectI2C();
+    void connectUart();
+    void buildMainUI();
+    void buildGrid(lv_obj_t* parent);
+    void selectIfNeeded();
+
+    static void onTimer(lv_timer_t* t);
+    static void onI2CBtn(lv_event_t* e);
+    static void onUartBtn(lv_event_t* e);
+    void update();
+};