feat: display manager for e-ink framebuffer output and text messages

Co-authored-by: Cursor <cursoragent@cursor.com>

src/display_manager.h

@@ -0,0 +1,25 @@
+#pragma once
+
+#include <Arduino.h>
+#include <M5GFX.h>
+#include "config.h"
+#include "image_pipeline.h"
+#include "immich_client.h"
+#include "settings.h"
+
+class PowerManager;
+
+class DisplayManager {
+public:
+    void begin(PowerManager& power);
+    void showImage(const ProcessedImage& img);
+    void showMessage(const char* title, const char* body);
+    void showMetadata(const AssetInfo& info, uint8_t metaFlags, MetaPosition pos);
+
+private:
+    PowerManager* _power = nullptr;
+    M5GFX* _display = nullptr;
+
+    void triggerRefresh();
+    uint16_t paletteToColor565(uint8_t index);
+};