Phase 2: LittleFS storage manager on /spiffs + shared SPI2_HOST bus

main/storage_manager.h

@@ -0,0 +1,45 @@
+/*
+ * MTG RFID Companion - LittleFS storage manager
+ *
+ * Phase 2: Mounts LittleFS at /spiffs on the "storage" partition, seeds the
+ * default database files on first boot, and exposes file helpers used by the
+ * RFID/cache/web subsystems.
+ */
+
+#pragma once
+
+#include "esp_err.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define STORAGE_BASE_PATH   "/spiffs"
+#define STORAGE_MAPPINGS    STORAGE_BASE_PATH "/mappings.json"
+#define STORAGE_CARDS_DIR   STORAGE_BASE_PATH "/cards"
+
+/**
+ * @brief Mount LittleFS and seed default files.
+ * @return ESP_OK on success.
+ */
+esp_err_t storage_manager_init(void);
+
+/**
+ * @brief Check whether a file exists on the filesystem.
+ */
+bool storage_file_exists(const char *path);
+
+/**
+ * @brief Read an entire file into a heap allocated buffer (caller frees).
+ * @param[out] out_buf NULL terminated buffer; NULL and out_len=0 if missing.
+ */
+esp_err_t storage_read_text(const char *path, char **out_buf, size_t *out_len);
+
+/**
+ * @brief Write text (plus terminating newline) to a file atomically.
+ */
+esp_err_t storage_write_text(const char *path, const char *text);
+
+#ifdef __cplusplus
+}
+#endif