Extend browser admin lifecycle actions

Support browser reboot and HTTPS stop through deferred control, plus
exact
`web certificate rotate --force` handoff to the dispatcher. Add typed
request
validation and focused boundary and lifecycle coverage.

tests/web_cookie_auth/admin_test.c

@@ -14,6 +14,11 @@ static void (*timer_poll)(void *), (*pending_poll)(void *);
 static void *pending_argument;
 static httpd_req_t connected;
 static unsigned admin_closes;
+/* These endpoint tests never dispatch lifecycle commands. */
+void esp_restart(void) { assert(false); }
+esp_err_t web_server_stop(void) { assert(false); return ESP_FAIL; }
+esp_err_t web_server_start(void) { assert(false); return ESP_FAIL; }
+esp_err_t web_security_rotate_certificate(void) { assert(false); return ESP_FAIL; }
 void *heap_caps_calloc(size_t n, size_t size, unsigned caps) {
     assert(caps == (MALLOC_CAP_SPIRAM | MALLOC_CAP_8BIT)); return calloc(n, size);
 }

tests/web_cookie_auth/run.py

@@ -43,6 +43,7 @@ esp_err_t httpd_ws_respond_server_handshake(httpd_req_t *, const char *);
 
 admin = "--admin" in sys.argv
 if admin:
+    HEADERS["esp_system.h"] = "#pragma once\nvoid esp_restart(void);\n"
     HEADERS["esp_heap_caps.h"] = """#pragma once
 #include <stddef.h>
 #define MALLOC_CAP_SPIRAM 1