Alinear panel y auth con la identidad B2B "Architectural Warmth"

Sustituye la paleta negra/azul B2C del panel del reformista por el verde
de marca, neutros cálidos y titulares en Instrument Serif de la landing B2B.
Añade tokens --color-primary-*, --color-stone-50 y --font-display al @theme.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

mvp/b2c/src/components/panel/LeadsView.tsx

@@ -117,7 +117,7 @@ function ToggleVista({ vista, onChange }: { vista: Vista; onChange: (v: Vista) =
             aria-pressed={activo}
             className={
               'inline-flex items-center gap-1.5 rounded-md px-3 py-1.5 text-xs font-semibold transition-colors ' +
-              (activo ? 'bg-black text-white' : 'text-gray-500 hover:text-black')
+              (activo ? 'bg-primary-700 text-white' : 'text-gray-500 hover:text-primary-700')
             }
           >
             <svg
@@ -148,7 +148,7 @@ function Tarjeta({ l }: { l: PanelLead }) {
       className="group flex flex-col gap-3 rounded-xl border border-gray-200 bg-white p-4 transition hover:border-gray-400 hover:shadow-sm"
     >
       <div className="flex items-start gap-3">
-        <span className="flex h-11 w-11 shrink-0 items-center justify-center rounded-full bg-gray-900 text-sm font-bold text-white">
+        <span className="flex h-11 w-11 shrink-0 items-center justify-center rounded-full bg-primary-700 text-sm font-bold text-white">
           {iniciales(l.nombre)}
         </span>
         <div className="min-w-0 flex-1">