feat(system_init): introduce pre-scheduler and pre-app main handler registrations

- Added macros for registering handlers to run before the scheduler and app main.
- Updated various components to utilize the new registration system for initialization.
- Refactored app startup logic to streamline initialization sequence.

components/esp_system/include/esp_private/esp_sys_event_app_init.h

@@ -0,0 +1,47 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#pragma once
+
+#include "esp_cpu.h"
+#include "esp_private/esp_sys_event.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Register a handler to run on core 0 immediately before the scheduler starts
+ */
+#define ESP_PRE_SCHEDULER_HANDLER_REGISTER(fn, priority) \
+    static esp_err_t fn(void *user_arg, void *ctx); \
+    _ESP_SYS_EVENT_REGISTER(PRE_SCHEDULER, priority, __esp_pre_scheduler_##fn) \
+    { \
+        if (esp_cpu_get_core_id() != 0) { \
+            return ESP_OK; \
+        } \
+        return fn(user_arg, ctx); \
+    } \
+    static esp_err_t fn(void *user_arg, void *ctx)
+
+/**
+ * @brief Register a handler to run on every core immediately before its scheduler starts
+ */
+#define ESP_PRE_SCHEDULER_HANDLER_REGISTER_PER_CPU(fn, priority) \
+    _ESP_SYS_EVENT_REGISTER(PRE_SCHEDULER, priority, fn)
+
+/**
+ * @brief Register a handler to run in the main task immediately before app_main
+ *
+ * Handlers run in ascending priority order after all CPUs have completed
+ * FreeRTOS initialization. The scheduler and heap allocator are available.
+ */
+#define ESP_PRE_APP_MAIN_HANDLER_REGISTER(fn, priority) \
+    _ESP_SYS_EVENT_REGISTER(PRE_APP_MAIN, priority, fn)
+
+#ifdef __cplusplus
+}
+#endif

components/esp_system/include/esp_sys_event_list.inc

@@ -34,6 +34,8 @@
 #define _ESP_SYS_EVENT_SECTION_SHUTDOWN                     esysev_shdn
 #define _ESP_SYS_EVENT_SECTION_SYSTEM_INIT_CORE             esysev_initc
 #define _ESP_SYS_EVENT_SECTION_SYSTEM_INIT_SECONDARY        esysev_inits
+#define _ESP_SYS_EVENT_SECTION_PRE_SCHEDULER                esysev_presc
+#define _ESP_SYS_EVENT_SECTION_PRE_APP_MAIN                 esysev_pream
 #define _ESP_SYS_EVENT_SECTION_PANIC                        esysev_panic
 #define _ESP_SYS_EVENT_SECTION_PANIC_EARLY_BREAK            esysev_paneb
 #endif
@@ -42,5 +44,7 @@
 ESP_SYS_EVENT_DEF(SHUTDOWN)
 ESP_SYS_EVENT_DEF(SYSTEM_INIT_CORE)
 ESP_SYS_EVENT_DEF(SYSTEM_INIT_SECONDARY)
+ESP_SYS_EVENT_DEF(PRE_SCHEDULER)
+ESP_SYS_EVENT_DEF(PRE_APP_MAIN)
 ESP_SYS_EVENT_DEF(PANIC)
 ESP_SYS_EVENT_DEF(PANIC_EARLY_BREAK)