Introduce StateManager class for persisting state to EEPROM.

examples/Gravity/save_state.h

@@ -0,0 +1,54 @@
+// File: save_state.h
+
+#ifndef SAVE_STATE_H
+#define SAVE_STATE_H
+
+#include <Arduino.h>
+#include <gravity.h> // We need this for OUTPUT_COUNT
+
+// Forward-declare AppState to avoid circular dependencies.
+struct AppState; 
+
+// Forward-declare the Source enum as well.
+enum Source;
+
+// Define the constants for the current firmware.
+const char CURRENT_SKETCH_NAME[] = "Gravity";
+const float CURRENT_SKETCH_VERSION = 0.2f; // You could increment this to 0.2 if you want to force a reset
+
+/**
+ * @brief Manages saving and loading of the application state to and from EEPROM.
+ */
+class StateManager {
+public:
+    bool initialize(AppState& app);
+    void save(const AppState& app);
+    void reset(AppState& app);
+
+private:
+    // This struct holds the data that identifies the firmware version.
+    struct Metadata {
+        char sketchName[16];
+        float version;
+    };
+    struct ChannelState {
+        byte base_clock_mod_index;
+        byte base_probability;
+        byte base_duty_cycle;
+        byte base_offset;
+        byte cv_source;      // We'll store the CvSource enum as a byte
+        byte cv_destination; // We'll store the CvDestination enum as a byte
+    };
+    // This struct holds all the parameters we want to save.
+    struct EepromData {
+        int selected_param;
+        byte selected_channel;
+        byte selected_source;
+        ChannelState channel_data[OUTPUT_COUNT]; 
+    };
+
+    bool isDataValid();
+    void writeMetadata();
+};
+
+#endif // SAVE_STATE_H