Add 'business' profile type and category

Business accounts are cli profiles with businessAddress=True, so each connecting
customer gets their own group chat (handled via the existing chat UI) with an
optional welcome auto-reply. New BUSINESS_TYPES, a /business page + sidebar entry,
and a business variant of the create form. profile/chat pages route via a
_category helper. Adds business_test.py (customer connects -> lands in a business
group, not a direct contact) — passes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

manager/templates/base.html

@@ -266,6 +266,7 @@
     </a>
     <nav class="side-nav">
       <a href="/users"    {% if nav_active == 'users'    %}class="active"{% endif %}><span class="ico">👤</span><span class="lbl">Users</span></a>
+      <a href="/business" {% if nav_active == 'business' %}class="active"{% endif %}><span class="ico">💼</span><span class="lbl">Business</span></a>
       <a href="/bots"     {% if nav_active == 'bots'     %}class="active"{% endif %}><span class="ico">🤖</span><span class="lbl">Bots</span></a>
       <a href="https://simplex.chat/file/" target="_blank" rel="noopener"><span class="ico">📁</span><span class="lbl">File upload</span></a>
       <a href="/notifications" class="nav-sep {% if nav_active == 'notifications' %}active{% endif %}"><span class="ico">🔔</span><span class="lbl">Notifications</span><span class="notif-badge" id="notif-badge" style="display:none;"></span></a>