Expand admin SSH command capabilities

Add per-session history, tab completion, interactive prompts, and
bounded input handling. Support deferred lifecycle and host-key actions
after output drains, and document the expanded administration workflow.

src/admin_ssh_console.h

@@ -23,6 +23,15 @@ typedef struct {
     uint32_t slot_generation;
 } admin_ssh_console_token_t;
 
+typedef enum {
+    ADMIN_SSH_DEFER_NONE = 0,
+    ADMIN_SSH_DEFER_REBOOT,
+    ADMIN_SSH_DEFER_STOP,
+    ADMIN_SSH_DEFER_DISCONNECT,
+    ADMIN_SSH_DEFER_HOST_KEY_ROTATE,
+    ADMIN_SSH_DEFER_HOST_KEY_RESET,
+} admin_ssh_deferred_action_type_t;
+
 typedef struct {
     bool active;
     bool command_pending;
@@ -40,6 +49,11 @@ esp_err_t admin_ssh_console_start_uart_frontend(void);
 /* Valid only while a registered command callback runs on the dispatcher task. */
 bool admin_ssh_console_dispatch_is_remote(void);
 const user_principal_t *admin_ssh_console_dispatch_principal(void);
+esp_err_t admin_ssh_console_dispatch_read_input(
+    const char *prompt, uint8_t *output, size_t capacity,
+    bool hidden, size_t *output_length);
+esp_err_t admin_ssh_console_dispatch_defer(
+    admin_ssh_deferred_action_type_t action, uint32_t argument);
 
 /* The token and principal are copied; no SSH or socket objects cross this boundary. */
 esp_err_t admin_ssh_console_open(const admin_ssh_console_token_t *token,