Release: add preference to hide new-chat welcome panel (#6183, @vaidu-ai) (#6387)

* feat: add option to hide new-chat welcome panel

* Release: add preference to hide new-chat welcome panel (#6183, @vaidu-ai)

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Co-authored-by: vaidu-ai <im@vaidu.net>
Co-authored-by: nesquena-hermes <agent@nesquena-hermes>

static/style.css

@@ -2513,6 +2513,7 @@
   @keyframes pulse{0%,80%,100%{opacity:.2;transform:scale(.8)}40%{opacity:.8;transform:scale(1)}}
   .empty-state{flex:1;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:12px;padding:40px;color:var(--muted);}
   .empty-state.no-suggestions .suggestion-grid{display:none}
+  .empty-state.no-welcome{display:none}
   /* Empty-state brand mark: a free-breathing winged caduceus with a soft
      "spirit" bloom behind it — no app-icon tile. Glow + mark gradient are
      tuned separately for dark vs light themes (see --logo-glow / .hm-g* below). */