Confirm changes automatically from the client that made them

A change made over the network answers with a one-time confirm_token
and closes its connection (HTTP/2: a GOAWAY). The web UI and hc send the
token straight back to /confirm, which accepts it only for the newest
change, from the same user and API token, the same address, and over a
new connection: proof that the client can still reach the API through
the new ruleset (an established connection would get through anyway). A
change that cuts its client off can't be confirmed so, and rolls back by
itself. The setting manual_confirm (hc settings set --auto-confirm off)
and hc --no-confirm leave confirming to a person. Changes through the
local socket still need no confirmation. e2e: 136 checks, among them a
lockout change rolled back without anyone confirming.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/web/static/assets/pages/settings.js

@@ -27,6 +27,7 @@ export async function render(el) {
   const v6 = listEditor(s.antispoof_v6, { addLabel: "Add" });
   const flow = listEditor(s.flowtable_devices, { suggestions: ifs.map((i) => i.name), placeholder: "wan", addLabel: "Add device" });
   const probation = input({ value: fmtSeconds(s.probation_seconds || 120), class: "short" });
+  const manual = checkbox("a person confirms each change (otherwise the browser or hc that made it confirms it by itself, once it reaches Housecarl again over a new connection)", s.manual_confirm);
   const err = h("div");
   const save = async (dry) => {
     mount(err);
@@ -37,7 +38,7 @@ export async function render(el) {
     try {
       const r = await change("PATCH", "/settings", { input_policy: input_.value, forward_policy: forward.value, output_policy: output.value,
         log_policy_drops: logDrops.input.checked, builtins, own_prefixes: own.value(), antispoof_v4: v4.value(), antispoof_v6: v6.value(),
-        flowtable_devices: flow.value(), probation_seconds: p === 120 ? 0 : p }, { query: dry ? { dry_run: 1 } : undefined });
+        flowtable_devices: flow.value(), probation_seconds: p === 120 ? 0 : p, manual_confirm: manual.input.checked }, { query: dry ? { dry_run: 1 } : undefined });
       if (!dry && (r.applied || r.staged)) rerender();
     } catch (e) { mount(err, errorBox(e)); }
   };
@@ -54,7 +55,8 @@ export async function render(el) {
       field("Antispoof IPv4", v4),
       field("Antispoof IPv6", v6),
       field("Flowtable", flow, "Forwarded TCP and UDP between these devices skip the rules once established (fast path). Exact names; none: off."),
-      field("Probation", probation, "How long a change made here has to be confirmed before it is rolled back.")),
+      field("Probation", probation, "How long a change made over the network has to be confirmed before it is rolled back."),
+      h("label"), manual),
     err,
     write ? h("div", { class: "actions form-actions" },
       h("button", { class: "primary", onclick: () => save(false) }, "Save"),