feat: nombre y logo de empresa configurables (solo dev, no desplegado a prod)

Nueva marca configurable desde Configuracion -> Empresa (solo superadmin): nombre y logo,
guardados en system_settings (mismo patron que SMTP, sin tabla nueva). Nuevo endpoint publico
GET /api/company (+ /logo) para que login/registro/recuperacion de clave puedan mostrar la marca
antes de iniciar sesion. Sin configurar, se ve "LinkedCorp" y el logo estatico de siempre.

Probado en dev (build + Playwright: panel de Configuracion, sidebar expandido/compacto, login
publico), sin desplegar a produccion por pedido explicito del usuario -- este commit sirve de
punto de control en git antes de decidir el despliegue.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

frontend/src/pages/Configuracion/CompanySettingsPanel.jsx

@@ -0,0 +1,71 @@
+import { useEffect, useRef, useState } from 'react';
+import { Save, Upload } from 'lucide-react';
+import { useUi } from '../../context/ui-context.jsx';
+import { useBranding } from '../../context/branding-context.jsx';
+import { useAsync, useAction } from '../../hooks/useAsync.js';
+import { getCompanyInfo, updateCompanyInfo } from '../../services/company.js';
+import { Field } from '../../components/Field.jsx';
+import { Button } from '../../components/Button.jsx';
+
+export default function CompanySettingsPanel() {
+  const { t, pushToast } = useUi();
+  const branding = useBranding();
+  const runAction = useAction();
+  const { data: company, reload } = useAsync(getCompanyInfo, []);
+  const [name, setName] = useState('');
+  const [logoFile, setLogoFile] = useState(null);
+  const [preview, setPreview] = useState(null);
+  const fileInputRef = useRef(null);
+
+  useEffect(() => {
+    if (company) setName(company.name);
+  }, [company]);
+
+  useEffect(() => {
+    if (!logoFile) { setPreview(null); return; }
+    const url = URL.createObjectURL(logoFile);
+    setPreview(url);
+    return () => URL.revokeObjectURL(url);
+  }, [logoFile]);
+
+  async function save() {
+    await runAction(async () => {
+      await updateCompanyInfo({ name, logoFile });
+      setLogoFile(null);
+      if (fileInputRef.current) fileInputRef.current.value = '';
+      await reload();
+      await branding.reload();
+      pushToast({ tone: 'success', message: t('common_saved') });
+    });
+  }
+
+  if (!company) return <div className="text-muted">{t('common_loading')}</div>;
+
+  const currentLogoSrc = preview || branding.logoUrl;
+
+  return (
+    <div>
+      <Field label={t('company_name')}>
+        <input className="input" value={name} onChange={(e) => setName(e.target.value)} placeholder="LinkedCorp" />
+      </Field>
+      <Field label={t('company_logo')} hint={t('company_logo_hint')}>
+        <div style={{ display: 'flex', alignItems: 'center', gap: 14 }}>
+          <div className="company-logo-preview">
+            {currentLogoSrc ? <img src={currentLogoSrc} alt={name} /> : <span className="text-muted" style={{ fontSize: '.7rem' }}>{t('company_logo_none')}</span>}
+          </div>
+          <input
+            ref={fileInputRef}
+            type="file"
+            accept="image/png,image/jpeg,image/webp,image/svg+xml"
+            style={{ display: 'none' }}
+            onChange={(e) => setLogoFile(e.target.files?.[0] || null)}
+          />
+          <Button variant="standard" icon={Upload} onClick={() => fileInputRef.current?.click()}>
+            {t('company_logo_choose')}
+          </Button>
+        </div>
+      </Field>
+      <Button variant="accent" icon={Save} onClick={save}>{t('common_save')}</Button>
+    </div>
+  );
+}

frontend/src/pages/Configuracion/ConfiguracionPage.jsx

@@ -1,5 +1,5 @@
 import { Navigate } from 'react-router-dom';
-import { Palette, ListChecks, Flag, FolderKanban, Layers, Mail } from 'lucide-react';
+import { Palette, ListChecks, Flag, FolderKanban, Layers, Mail, Building2 } from 'lucide-react';
 import { useUi } from '../../context/ui-context.jsx';
 import { useAuth } from '../../context/auth-context.jsx';
 import { Expander } from '../../components/Expander.jsx';
@@ -7,6 +7,7 @@ import { Field, FieldRow } from '../../components/Field.jsx';
 import { ComboBox } from '../../components/ComboBox.jsx';
 import { CatalogEditor } from './CatalogEditor.jsx';
 import SmtpSettingsPanel from './SmtpSettingsPanel.jsx';
+import CompanySettingsPanel from './CompanySettingsPanel.jsx';
 
 export default function ConfiguracionPage() {
   const { t, theme, setTheme, lang, setLang, buttonMode, setButtonMode } = useUi();
@@ -20,7 +21,11 @@ export default function ConfiguracionPage() {
     <div>
       <h2 className="page-title mt-0" style={{ marginBottom: 16 }}>{t('config_title')}</h2>
 
-      <Expander icon={Palette} title={t('config_appearance')} defaultOpen>
+      <Expander icon={Building2} title={t('config_company')} defaultOpen>
+        <CompanySettingsPanel />
+      </Expander>
+
+      <Expander icon={Palette} title={t('config_appearance')}>
         <FieldRow>
           <Field label="Tema / Theme">
             <ComboBox