Add admin serial settings view

src/web_httpd_adapter.c

@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-3.0-only */
 /* Deliberately isolated dependency on the installed IDF HTTPD layout. */
 #include "web_httpd_adapter.h"
+#include <stdlib.h>
 #include <string.h>
 #include <strings.h>
 #include "esp_idf_version.h"
@@ -104,3 +105,32 @@ bool web_httpd_unread_body(httpd_req_t *request)
     const struct httpd_req_aux *aux = request->aux;
     return aux && aux->remaining_len != 0;
 }
+
+esp_err_t web_httpd_register_optional_get(httpd_handle_t server, const httpd_uri_t *uri)
+{
+    struct httpd_data *hd = server;
+    if (!hd || !uri || !uri->uri || !uri->handler || uri->method != HTTP_GET ||
+        uri->is_websocket || uri->supported_subprotocol || hd->config.uri_match_fn)
+        return ESP_ERR_INVALID_ARG;
+    size_t length = 0;
+    while (length < 128 && uri->uri[length]) ++length;
+    if (!length || length == 128) return ESP_ERR_INVALID_ARG;
+    int slot = -1;
+    for (unsigned i = 0; i < hd->config.max_uri_handlers; ++i) {
+        if (!hd->hd_calls[i]) { if (slot < 0) slot = (int)i; }
+        else if (!strcmp(hd->hd_calls[i]->uri, uri->uri) && hd->hd_calls[i]->method == HTTP_GET)
+            return ESP_ERR_INVALID_STATE;
+    }
+    if (slot < 0) return ESP_ERR_NO_MEM;
+    /* IDF 5.5.0 publishes its descriptor before strdup; strdup failure leaves a
+     * freed hd_calls entry. Optional registration must leave the table intact. */
+    httpd_uri_t *copy = malloc(sizeof(*copy));
+    if (!copy) return ESP_ERR_NO_MEM;
+    char *name = malloc(length + 1);
+    if (!name) { free(copy); return ESP_ERR_NO_MEM; }
+    memcpy(name, uri->uri, length + 1);
+    *copy = *uri;
+    copy->uri = name;
+    hd->hd_calls[slot] = copy;
+    return ESP_OK;
+}