fix(account): one form and one Save for your account; the same for an account's page in Users

Operator review of the Account page: two sections with two different
save buttons, one stuck to the next card and one beside a squeezed hint.
- Account: time zone and Email are one form; POST /account/ saves both,
  nothing unless all of it is valid. /account/email is gone.
- Users › account: Name and Email are one form; the rename route also
  saves the email switches. /settings/users/<id>/email is gone.
- The Email section is a plain section now (email_section); its hint sits
  under the switches, names the zone as the picker does, and links
  Notifications only for an admin.
- apply_email_form leaves a switch the form doesn't carry as it is.

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

steward/templates/settings/user.html

@@ -5,7 +5,7 @@
 {% extends "base.html" %}
 {% from "_macros.html" import crumbs, page_header, status_badge %}
 {% from "settings/_tabs.html" import settings_tabs %}
-{% from "account/_email_choices.html" import email_choices with context %}
+{% from "account/_email_choices.html" import email_section with context %}
 {% block title %}{{ user.username }} — Users — Steward{% endblock %}
 {% block section_tabs %}{{ settings_tabs("users") }}{% endblock %}
 {% block breadcrumb %}{{ crumbs([("Settings", "/settings/"), ("Users", "/settings/users/"), (user.username, "")]) }}{% endblock %}
@@ -38,12 +38,13 @@
       </div>
     </div>
     {% if not local %}<p class="field-hint">{{ source }} finds this account by its own id, not by name, so renaming it here does not stop it signing in.</p>{% endif %}
-    <button type="submit" class="btn">Save</button>
   </section>
-</form>
 
-{% if not reachable %}<p class="field-hint tone-warn">{{ user.email }} isn't an address mail can reach, so this account gets no email. Set a real one above.</p>{% endif %}
-{{ email_choices(user, defaults, "/settings/users/" ~ user.id ~ "/email", with_address=false) }}
+  {% set zone = (user.time_zone or "UTC").split("/", 1)[-1]|replace("_", " ") %}
+  {{ email_section(user, defaults, "this account's own zone (" ~ zone ~ ")", with_address=false, unreachable=not reachable) }}
+
+  <div class="form-actions"><button type="submit" class="btn">Save</button></div>
+</form>
 
 <section class="card form-section" aria-labelledby="u-role">
   <h2 id="u-role" class="section-title">Role</h2>