feat(pos): configuracion funcional — sucursales, empleados, tema

Replace hardcoded demo data in the config page with real API calls.
Branches and employees now load from /pos/api/config/* endpoints,
with create modals for both. Business data tab reads tenant_config
(read-only). Theme selector was already working and is preserved.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pos/blueprints/config_bp.py

@@ -126,6 +126,29 @@ def create_employee():
     return jsonify({'id': emp_id, 'message': 'Employee created'}), 201
 
 
+@config_bp.route('/business', methods=['GET'])
+@require_auth()
+def get_business():
+    """Read-only tenant business info from tenant_config."""
+    conn = get_tenant_conn(g.tenant_id)
+    cur = conn.cursor()
+    cur.execute("SELECT key, value FROM tenant_config WHERE key LIKE 'tenant_%'")
+    cfg = {}
+    for row in cur.fetchall():
+        cfg[row[0]] = row[1]
+    cur.close()
+    conn.close()
+    return jsonify({
+        'razon_social': cfg.get('tenant_razon_social', ''),
+        'nombre': cfg.get('tenant_nombre', cfg.get('tenant_razon_social', '')),
+        'rfc': cfg.get('tenant_rfc', ''),
+        'regimen_fiscal': cfg.get('tenant_regimen_fiscal', ''),
+        'direccion': cfg.get('tenant_direccion', ''),
+        'telefono': cfg.get('tenant_telefono', ''),
+        'email': cfg.get('tenant_email', ''),
+    })
+
+
 @config_bp.route('/theme', methods=['GET'])
 @require_auth()
 def get_theme():