Move UART command handlers into main/cmd/ for clearer layout.

Add cmd/ to CMake include paths and update documentation paths.

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

main/cmd/cmd_handler.h

@@ -0,0 +1,26 @@
+#ifndef CMD_HANDLER_H
+#define CMD_HANDLER_H
+
+#include "esp_err.h"
+#include "freertos/idf_additions.h"
+
+typedef struct {
+  uint16_t msg_id;
+  uint8_t *payload;
+  size_t len;
+} generic_msg_t;
+
+typedef void (*msg_callback_t)(const uint8_t *data, size_t len);
+
+typedef struct {
+  uint16_t msg_id;
+  msg_callback_t callback;
+} msg_binding_t;
+
+void init_cmdHandler(QueueHandle_t queue);
+void vCmdDispatcherTask(void *param);
+
+esp_err_t msg_register_handler(uint16_t id, msg_callback_t cb);
+esp_err_t msg_post(uint16_t id, const uint8_t *data, size_t len);
+
+#endif