feat: the workspace at /workspace; Настройки show the assistant's model as set, key included, and PostgreSQL's fields only when chosen, its two buttons on one line; pages come in softly

internal/server/web/templates/layout.html

@@ -9,7 +9,7 @@
   <div class="brand"><a class="home" href="/" title="К списку машин">LPRA</a> · <span id="brandtitle">Удалённый доступ</span></div>
   <nav>
     <a href="/" data-nav="machines">Машины</a>
-    <a href="/terminal" data-nav="terminal">WorkSpace</a>
+    <a href="/workspace" data-nav="terminal">WorkSpace</a>
     {{if .IsAdmin}}<a href="/settings" data-nav="settings">Настройки</a>{{end}}
     <span id="status" class="muted"></span>
     <button type="button" class="btn ghost icon acct-btn" id="acct" title="Аккаунт" aria-label="Аккаунт"><svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><circle cx="12" cy="8" r="4"/><path d="M4 21a8 8 0 0 1 16 0"/></svg></button>