Kernel improvements (#485)

* **New Features**
  * Added public accessors for querying module/device start and ready state.

* **Refactor**
  * Internal state moved to opaque internal objects; module/device/driver initializers now explicitly initialize internal pointers.
  * Lifecycle handling updated to construct/destruct internal state and use accessors.

* **Tests**
  * Tests updated to use public accessors and explicit construct/destruct lifecycle calls.

* **Chores**
  * Test build/include paths and small metadata updated.

Tests/TactilityFreeRtos/Source/PubSubTest.cpp

@@ -0,0 +1,36 @@
+#include "doctest.h"
+#include <Tactility/PubSub.h>
+
+using namespace tt;
+
+TEST_CASE("PubSub publishing with no subscriptions should not crash") {
+    PubSub<int> pubsub;
+    pubsub.publish(1);
+}
+
+TEST_CASE("PubSub subscription receives published data") {
+    PubSub<int> pubsub;
+    int value = 0;
+
+    auto subscription = pubsub.subscribe([&value](auto newValue) {
+        value = newValue;
+    });
+    pubsub.publish(1);
+
+    pubsub.unsubscribe(subscription);
+
+    CHECK_EQ(value, 1);
+}
+
+TEST_CASE("PubSub unsubscribed subscription does not receive published data") {
+    PubSub<int> pubsub;
+    int value = 0;
+
+    auto subscription = pubsub.subscribe([&value](auto newValue) {
+        value = newValue;
+    });
+    pubsub.unsubscribe(subscription);
+    pubsub.publish(1);
+
+    CHECK_EQ(value, 0);
+}