Implement Read-Only OLED Status UI

src/local_status_ui.h

@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-3.0-only */
+/* Read-only local status UI for the optional OLED. */
+
+#pragma once
+
+#include "esp_err.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * Starts the low-priority status renderer. The task reads public service
+ * snapshots only; it never becomes a broker client or changes service state.
+ * The OLED and buttons are optional, so a missing display is not an error.
+ */
+esp_err_t local_status_ui_start(void);
+
+/* Preserve a manually selected display diagnostic for a bounded interval. */
+void local_status_ui_hold_for_diagnostics(void);
+
+#ifdef __cplusplus
+}
+#endif