Let people set their own ntfy topic under Account

The first-run checklist's first step is "Set where your pages go", and its
button navigated to /more — which had no field for it. Every new user was
sent to a page that could not do the thing it sent them there for, and the
only ways to actually set a topic were curl or asking an administrator.
That has been true since the checklist shipped in v0.15.0.

Account now has a Notifications section above the password form: the topic,
prefilled and saved through the endpoint that already existed, and a Send a
test push button. The test is offered only once a topic is saved, because
it publishes what the server has stored rather than what is half-typed in
the field, and a button that silently tested the previous value would be
worse than no button.

Saving assigns the response to state.me.user, so the checklist stops asking
and the test button appears without a reload. Clearing works by saving an
empty topic: the server treats that as "no topic of their own" rather than
an error, and returns a user with ntfy_topic absent — it is omitempty — so
the form reads the cleared state from the response rather than assuming it.

The copy says the topic is a shared secret, because people reach for their
own name and it is the only thing between a stranger and their pages. Same
reason the topic stays out of an incident's timeline, which every API key
can read.

No server change: PUT /api/users/{id}/notify has been self-or-admin since
#3 and needed nothing. Only the ntfy topic is per-person — the server is
the install's one TERDUT_NTFY_URL and is not something a user picks.

Also drops a line on that page still sending people to terdut-tui for user
management, which stopped being true one release ago.

Claude-Session: https://claude.ai/code/session_01RHPj4ggeFdEjKKfm4SHbD7

internal/web/static/js/account.js

@@ -23,6 +23,9 @@ function render() {
         h('div', { class: 'account-name', text: user.username }),
         h('div', { class: 'account-email', text: user.email }))),
 
+    h('div', { class: 'page-head' }, h('h2', { text: 'Notifications' })),
+    notifyForm(user),
+
     h('div', { class: 'page-head' }, h('h2', { text: hasPassword ? 'Change password' : 'Set a password' })),
     passwordForm(user, hasPassword),
 
@@ -32,10 +35,91 @@ function render() {
 
     h('div', { class: 'page-head' }),
     h('button', { class: 'btn btn-block', type: 'button', onclick: signOut }, icon('logout'), 'Sign out'),
-    h('p', { class: 'foot-note', text: 'Schedule editing, statistics and user management are in terdut-tui for now.' }),
+    h('p', { class: 'foot-note', text: 'Statistics are in terdut-tui for now.' }),
   );
 }
 
+// Where this user's pages go. The onboarding checklist's first step sends
+// people here for it, and until now there was nothing here to send them to:
+// the topic could only be set with curl or by an administrator.
+//
+// The topic is the whole address — the server it is published to is the
+// install's one ntfy, set in the deployment and not something a user picks.
+function notifyForm(user) {
+  const err = h('p', { class: 'form-error', role: 'alert', hidden: true });
+  const ok = h('p', { class: 'form-ok', role: 'status', hidden: true });
+  const topic = h('input', {
+    name: 'ntfy_topic', type: 'text', autocomplete: 'off',
+    autocapitalize: 'none', spellcheck: false,
+    value: user.ntfy_topic || '',
+    placeholder: 'terdut-a7f3c91e',
+  });
+  const submit = h('button', { class: 'btn btn-primary', type: 'submit', text: 'Save topic' });
+
+  // Only offered once a topic is saved: the test publishes to whatever the
+  // server has stored, not to whatever is half-typed in the field.
+  const test = h('button', {
+    class: 'btn', type: 'button', text: 'Send a test push',
+    hidden: !user.ntfy_topic,
+    onclick: async () => {
+      err.hidden = true;
+      ok.hidden = true;
+      test.disabled = true;
+      try {
+        await api.testNotification();
+        ok.textContent = 'Sent. If nothing arrives, the topic is wrong or ntfy is not reachable.';
+        ok.hidden = false;
+      } catch (ex) {
+        err.textContent = ex.message;
+        err.hidden = false;
+      } finally {
+        test.disabled = false;
+      }
+    },
+  });
+
+  const form = h('form', { class: 'card pw-form' },
+    h('label', {},
+      h('span', { text: 'ntfy topic' }),
+      topic),
+    h('p', { class: 'muted small' },
+      'Subscribe to this topic in the ntfy app and incidents assigned to you ',
+      'reach your phone. Leave it empty and they page the team’s fallback ',
+      'topic instead.'),
+    // Worth saying plainly: people reach for their own name, and the topic is
+    // the only thing standing between a stranger and their pages.
+    h('p', { class: 'muted small' },
+      'Anyone who knows the topic can read your pages and publish to it, so ',
+      'pick something unguessable rather than your name.'),
+    err, ok,
+    h('div', { class: 'row-actions' }, submit, test),
+  );
+
+  form.addEventListener('submit', async (e) => {
+    e.preventDefault();
+    err.hidden = true;
+    ok.hidden = true;
+    submit.disabled = true;
+    try {
+      const updated = await api.setNotifyTarget(user.id, topic.value.trim());
+      // Keep the cached user in step, so the onboarding checklist stops
+      // asking for this and the test button appears without a reload.
+      state.me.user = updated;
+      ok.textContent = updated.ntfy_topic
+        ? 'Topic saved.'
+        : 'Topic cleared. Your pages go to the team’s fallback topic.';
+      ok.hidden = false;
+      test.hidden = !updated.ntfy_topic;
+    } catch (ex) {
+      err.textContent = ex.message;
+      err.hidden = false;
+    } finally {
+      submit.disabled = false;
+    }
+  });
+  return form;
+}
+
 function passwordForm(user, hasPassword) {
   const err = h('p', { class: 'form-error', role: 'alert', hidden: true });
   const ok = h('p', { class: 'form-ok', role: 'status', hidden: true });