feat(fase4): add FlowTemplates frontend page

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/pages/FlowTemplates.tsx

@@ -0,0 +1,157 @@
+import { useState } from 'react';
+import {
+  Card,
+  Row,
+  Col,
+  Button,
+  Modal,
+  Input,
+  Typography,
+  Tag,
+  Empty,
+  message,
+} from 'antd';
+import { CopyOutlined } from '@ant-design/icons';
+import { useQuery, useMutation } from '@tanstack/react-query';
+import { useNavigate } from 'react-router-dom';
+import { apiClient } from '../api/client';
+
+const { Title, Text, Paragraph } = Typography;
+
+interface FlowTemplate {
+  id: string;
+  name: string;
+  description: string | null;
+  category: string;
+  nodes: unknown[];
+}
+
+const categoryColors: Record<string, string> = {
+  general: 'blue',
+  sales: 'green',
+  support: 'orange',
+  marketing: 'purple',
+};
+
+export default function FlowTemplates() {
+  const [isCreateModalOpen, setIsCreateModalOpen] = useState(false);
+  const [selectedTemplate, setSelectedTemplate] = useState<FlowTemplate | null>(null);
+  const [flowName, setFlowName] = useState('');
+  const navigate = useNavigate();
+
+  const { data: templates, isLoading } = useQuery({
+    queryKey: ['flow-templates'],
+    queryFn: () => apiClient.get<FlowTemplate[]>('/api/flow-templates'),
+  });
+
+  const useTemplateMutation = useMutation({
+    mutationFn: ({ templateId, name }: { templateId: string; name: string }) => {
+      const encodedName = encodeURIComponent(name);
+      return apiClient.post<{ flow_id: string }>(
+        `/api/flow-templates/${templateId}/use?flow_name=${encodedName}`,
+        {}
+      );
+    },
+    onSuccess: (data) => {
+      message.success('Flujo creado desde plantilla');
+      setIsCreateModalOpen(false);
+      setSelectedTemplate(null);
+      setFlowName('');
+      navigate(`/flows/${data.flow_id}`);
+    },
+  });
+
+  function handleUseTemplate(template: FlowTemplate): void {
+    setSelectedTemplate(template);
+    setFlowName(`${template.name} - Copia`);
+    setIsCreateModalOpen(true);
+  }
+
+  function handleModalCancel(): void {
+    setIsCreateModalOpen(false);
+    setSelectedTemplate(null);
+  }
+
+  function handleModalOk(): void {
+    if (selectedTemplate && flowName) {
+      useTemplateMutation.mutate({ templateId: selectedTemplate.id, name: flowName });
+    }
+  }
+
+  function renderContent() {
+    if (isLoading) {
+      return <Card loading />;
+    }
+
+    if (!templates || templates.length === 0) {
+      return <Empty description="No hay plantillas disponibles" />;
+    }
+
+    return (
+      <Row gutter={[16, 16]}>
+        {templates.map((template) => (
+          <Col key={template.id} xs={24} sm={12} md={8} lg={6}>
+            <Card
+              hoverable
+              actions={[
+                <Button
+                  type="link"
+                  icon={<CopyOutlined />}
+                  onClick={() => handleUseTemplate(template)}
+                >
+                  Usar
+                </Button>,
+              ]}
+            >
+              <Card.Meta
+                title={template.name}
+                description={
+                  <>
+                    <Tag color={categoryColors[template.category] || 'default'}>
+                      {template.category}
+                    </Tag>
+                    <Paragraph ellipsis={{ rows: 2 }} style={{ marginTop: 8, marginBottom: 0 }}>
+                      {template.description || 'Sin descripcion'}
+                    </Paragraph>
+                    <Text type="secondary" style={{ fontSize: 12 }}>
+                      {template.nodes.length} nodos
+                    </Text>
+                  </>
+                }
+              />
+            </Card>
+          </Col>
+        ))}
+      </Row>
+    );
+  }
+
+  return (
+    <div>
+      <div style={{ display: 'flex', justifyContent: 'space-between', marginBottom: 24 }}>
+        <Title level={4} style={{ margin: 0 }}>Plantillas de Flujos</Title>
+      </div>
+
+      {renderContent()}
+
+      <Modal
+        title="Crear flujo desde plantilla"
+        open={isCreateModalOpen}
+        onCancel={handleModalCancel}
+        onOk={handleModalOk}
+        okText="Crear"
+        confirmLoading={useTemplateMutation.isPending}
+      >
+        <div style={{ marginBottom: 16 }}>
+          <Text strong>Plantilla: </Text>
+          <Text>{selectedTemplate?.name}</Text>
+        </div>
+        <Input
+          placeholder="Nombre del nuevo flujo"
+          value={flowName}
+          onChange={(e) => setFlowName(e.target.value)}
+        />
+      </Modal>
+    </div>
+  );
+}