Add Mago4 demo ERP with Python FastAPI

Implements a working in-memory ERP demo inspired by Mago4, covering
the core modules: dashboard with KPI widgets, customers, suppliers,
products, sales orders, purchase orders, and warehouse inventory.

- FastAPI backend with Pydantic models and REST API (auto-docs at /docs)
- Jinja2 HTML templates with Mago4-style UI (dark sidebar, blue/orange/
  green/red palette, Material Design icons)
- In-memory fake database seeded with sample customers, suppliers,
  products, and orders — ready to swap for SQLAlchemy + SQL Server
- Workarounds for Python 3.14 + Starlette 1.3 / Jinja2 compatibility
  (cache_size=0, new TemplateResponse(request, name, ctx) signature)
- launch.json for one-click preview; run.bat for manual startup

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

static/js/app.js

@@ -0,0 +1,120 @@
+// Utility functions for API calls
+async function apiCall(endpoint, method = 'GET', data = null) {
+    const options = {
+        method: method,
+        headers: {
+            'Content-Type': 'application/json',
+        }
+    };
+
+    if (data) {
+        options.body = JSON.stringify(data);
+    }
+
+    try {
+        const response = await fetch(endpoint, options);
+        if (!response.ok) {
+            throw new Error(`API Error: ${response.statusText}`);
+        }
+        return await response.json();
+    } catch (error) {
+        console.error('API call failed:', error);
+        showNotification('Errore nella richiesta', 'error');
+        throw error;
+    }
+}
+
+// Notification system
+function showNotification(message, type = 'info') {
+    const notification = document.createElement('div');
+    notification.className = `notification notification-${type}`;
+    notification.textContent = message;
+    notification.style.cssText = `
+        position: fixed;
+        top: 20px;
+        right: 20px;
+        padding: 12px 20px;
+        background-color: ${type === 'error' ? '#D32F2F' : '#1976D2'};
+        color: white;
+        border-radius: 4px;
+        box-shadow: 0 4px 12px rgba(0,0,0,0.2);
+        z-index: 2000;
+        animation: slideIn 0.3s ease-in-out;
+    `;
+
+    document.body.appendChild(notification);
+    setTimeout(() => notification.remove(), 3000);
+}
+
+// Format currency
+function formatCurrency(value) {
+    return new Intl.NumberFormat('it-IT', {
+        style: 'currency',
+        currency: 'EUR'
+    }).format(value);
+}
+
+// Format date
+function formatDate(dateString) {
+    const date = new Date(dateString);
+    return date.toLocaleDateString('it-IT');
+}
+
+// Initialize page animations
+document.addEventListener('DOMContentLoaded', function() {
+    // Add smooth scrolling
+    document.querySelectorAll('a[href^="#"]').forEach(anchor => {
+        anchor.addEventListener('click', function(e) {
+            e.preventDefault();
+            const target = document.querySelector(this.getAttribute('href'));
+            if (target) {
+                target.scrollIntoView({ behavior: 'smooth' });
+            }
+        });
+    });
+
+    // Add keyboard shortcuts
+    document.addEventListener('keydown', function(e) {
+        // Close modals with Escape
+        if (e.key === 'Escape') {
+            document.querySelectorAll('.modal.show').forEach(modal => {
+                modal.classList.remove('show');
+            });
+        }
+    });
+
+    // Initialize tooltips
+    document.querySelectorAll('[title]').forEach(element => {
+        element.style.cursor = 'help';
+    });
+});
+
+// Add CSS animation for notifications
+const style = document.createElement('style');
+style.textContent = `
+    @keyframes slideIn {
+        from {
+            transform: translateX(400px);
+            opacity: 0;
+        }
+        to {
+            transform: translateX(0);
+            opacity: 1;
+        }
+    }
+
+    .material-icons {
+        font-family: 'Material Icons';
+        font-weight: normal;
+        font-style: normal;
+        font-size: 24px;
+        display: inline-block;
+        line-height: 1;
+        text-transform: none;
+        letter-spacing: normal;
+        word-wrap: normal;
+        white-space: nowrap;
+        direction: ltr;
+    }
+`;
+document.head.appendChild(style);