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/console_completion.c

@@ -10,6 +10,11 @@
 #include "esp_console.h"
 #include "linenoise/linenoise.h"
 
+static const char *const s_root_candidates[] = {
+    "help", "status", "debug", "display", "serial", "broker", "usb", "user",
+    "wifi", "web", "ssh", "ping", "nslookup", "traceroute", "reboot", "memory",
+};
+
 /* Keep full-line candidate strings grouped by their registered root command. */
 static const char *const s_completion_candidates[] = {
     /* Hardware debug commands and safe fixed arguments. */
@@ -197,6 +202,49 @@ static const char *const s_completion_candidates[] = {
     "ssh reset --force",
 };
 
+bool console_completion_expand(const char *line, char *completed, size_t capacity)
+{
+    if (line == NULL || completed == NULL || capacity == 0U) {
+        return false;
+    }
+    size_t line_length = strlen(line);
+    const char *const *candidates = strchr(line, ' ') == NULL
+                                        ? s_root_candidates
+                                        : s_completion_candidates;
+    size_t candidate_count = strchr(line, ' ') == NULL
+                                 ? sizeof(s_root_candidates) / sizeof(s_root_candidates[0])
+                                 : sizeof(s_completion_candidates) /
+                                       sizeof(s_completion_candidates[0]);
+    const char *first = NULL;
+    size_t common_length = 0U;
+    for (size_t index = 0U; index < candidate_count; ++index) {
+        const char *candidate = candidates[index];
+        if (strncmp(candidate, line, line_length) != 0) {
+            continue;
+        }
+        if (first == NULL) {
+            first = candidate;
+            common_length = strlen(candidate);
+            continue;
+        }
+        size_t candidate_length = strlen(candidate);
+        if (common_length > candidate_length) {
+            common_length = candidate_length;
+        }
+        size_t offset = line_length;
+        while (offset < common_length && first[offset] == candidate[offset]) {
+            ++offset;
+        }
+        common_length = offset;
+    }
+    if (first == NULL || common_length <= line_length || common_length >= capacity) {
+        return false;
+    }
+    memcpy(completed, first, common_length);
+    completed[common_length] = '\0';
+    return true;
+}
+
 static ssize_t console_read_with_late_terminal_upgrade(int file_descriptor,
                                                        void *buffer,
                                                        size_t size)