copy: flip visible wordmark → Roundtable

Updates nav brand, page <title> blocks across all templates, and the
read-only share view footer. Removes duplicate Roundtable heading from
login card now that the nav wordmark reads correctly.

roundtable/templates/auth/login.html

@@ -1,9 +1,8 @@
 {% extends "base.html" %}
-{% block title %}Login — Fabled Scryer{% endblock %}
+{% block title %}Login — Roundtable{% endblock %}
 {% block content %}
 <div style="max-width:400px;margin:4rem auto;">
     <div class="card">
-        <h1 style="font-family: var(--font-serif); font-weight: 700; font-size: 2.75rem; color: var(--gold); text-align: center; margin: 0; line-height: 1.1; letter-spacing: 0.02em;">Roundtable</h1>
         <p style="color: var(--text-dim); font-family: var(--font-serif); font-style: italic; font-size: 1.15rem; text-align: center; margin: 0 0 1.5rem;">Under Watch, Under Care.</p>
         {% if error %}
         <div style="color:var(--red);font-size:0.88rem;margin-bottom:1rem;

roundtable/templates/auth/setup.html

@@ -1,5 +1,5 @@
 {% extends "base.html" %}
-{% block title %}First-Run Setup — Fabled Scryer{% endblock %}
+{% block title %}First-Run Setup — Roundtable{% endblock %}
 {% block content %}
 <div style="max-width:400px;margin:4rem auto;">
     <div class="card">