feat: Implement main application shell with navigation and color scheme toggle

- Added Appshell component with responsive navbar and main content area
- Integrated ColorSchemeToggle for light/dark mode switching
- Created Welcome component with styled title and introductory text
- Developed ChatPage for LLM interaction with WebSocket support
- Implemented Biblioteca for managing notes with rich text editor
- Added LoginPage for user authentication with error handling
- Introduced MessageList and MessageBubble components for chat messages
- Styled components with CSS modules for consistent design

frontend/src/frontend_domains/Experiments/Visualizaciones_Random.tsx

@@ -0,0 +1,53 @@
+import { AppShellWithMenu } from '../FitzStudio/Appshell/Appshell';
+import { Card, Grid, Title, Loader } from '@mantine/core';
+import { useEffect, useState } from 'react';
+import ReactECharts from 'echarts-for-react';
+
+type ChartOption = any;
+
+function useChartOption(endpoint: string) {
+  const [option, setOption] = useState<ChartOption | null>(null);
+  const [loading, setLoading] = useState(true);
+
+  useEffect(() => {
+    fetch(`/api/v1/charts/${endpoint}`)
+      .then((res) => res.json())
+      .then((json) => setOption(json))
+      .catch(console.error)
+      .finally(() => setLoading(false));
+  }, [endpoint]);
+
+  return { option, loading };
+}
+
+export function VisualizacionesRandom() {
+  const charts = [
+    { title: 'Gráfico de barras', endpoint: 'bar' },
+    { title: 'Gráfico de líneas', endpoint: 'line' },
+    { title: 'Gráfico de pastel', endpoint: 'pie' },
+    { title: 'Scatter plot', endpoint: 'scatter' },
+  ];
+
+  return (
+    <AppShellWithMenu>
+      <Grid>
+        {charts.map(({ title, endpoint }, idx) => {
+          const { option, loading } = useChartOption(endpoint);
+
+          return (
+            <Grid.Col span={{ base: 12, sm: 6, md: 6, lg: 3 }} key={idx}>
+              <Card shadow="sm" padding="lg" radius="md" withBorder>
+                <Title order={4}>{title}</Title>
+                {loading || !option ? (
+                  <Loader mt="md" />
+                ) : (
+                  <ReactECharts option={option} style={{ height: 250, marginTop: 16 }} />
+                )}
+              </Card>
+            </Grid.Col>
+          );
+        })}
+      </Grid>
+    </AppShellWithMenu>
+  );
+}