feat(pos): integrate design system for facturacion, contabilidad, dashboard, config, reportes

Replace 5 POS templates with updated design system pages using tokens.css.
Add routes for dashboard, config, and reports pages.
Create stub JS files for dashboard, config, and reports modules.

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

pos/static/js/dashboard.js

@@ -0,0 +1,113 @@
+// /home/Autopartes/pos/static/js/dashboard.js
+// Dashboard module: KPIs, charts, summary data
+
+const Dashboard = (() => {
+    function token() {
+        return localStorage.getItem('pos_token') || '';
+    }
+
+    function checkAuth() {
+        if (!token()) {
+            window.location.href = '/pos/login';
+            return false;
+        }
+        return true;
+    }
+
+    function headers() {
+        return { 'Authorization': `Bearer ${token()}`, 'Content-Type': 'application/json' };
+    }
+
+    function fmt(n) {
+        return parseFloat(n || 0).toLocaleString('es-MX', { minimumFractionDigits: 2, maximumFractionDigits: 2 });
+    }
+
+    // -------------------------------------------------------------------------
+    // Theme switcher
+    // -------------------------------------------------------------------------
+    function setTheme(theme) {
+        document.documentElement.setAttribute('data-theme', theme);
+        try { localStorage.setItem('nexus-theme', theme); } catch(e) {}
+        const btnInd = document.getElementById('btn-industrial');
+        const btnMod = document.getElementById('btn-modern');
+        if (btnInd) btnInd.classList.toggle('active', theme === 'industrial');
+        if (btnMod) btnMod.classList.toggle('active', theme === 'modern');
+    }
+    window.setTheme = setTheme;
+
+    // -------------------------------------------------------------------------
+    // Sidebar toggle (mobile)
+    // -------------------------------------------------------------------------
+    function toggleSidebar() {
+        const sidebar = document.getElementById('sidebar');
+        const overlay = document.getElementById('sidebar-overlay');
+        if (!sidebar) return;
+        const isOpen = sidebar.classList.contains('open');
+        sidebar.classList.toggle('open', !isOpen);
+        if (overlay) overlay.classList.toggle('open', !isOpen);
+        document.body.style.overflow = isOpen ? '' : 'hidden';
+    }
+    window.toggleSidebar = toggleSidebar;
+
+    function closeSidebar() {
+        const sidebar = document.getElementById('sidebar');
+        const overlay = document.getElementById('sidebar-overlay');
+        if (sidebar) sidebar.classList.remove('open');
+        if (overlay) overlay.classList.remove('open');
+        document.body.style.overflow = '';
+    }
+    window.closeSidebar = closeSidebar;
+
+    window.addEventListener('resize', function() {
+        if (window.innerWidth >= 768) closeSidebar();
+    });
+
+    // -------------------------------------------------------------------------
+    // Period selector
+    // -------------------------------------------------------------------------
+    function setPeriod(btn) {
+        btn.closest('.period-selector').querySelectorAll('.period-btn').forEach(function(b) {
+            b.classList.remove('active');
+        });
+        btn.classList.add('active');
+    }
+    window.setPeriod = setPeriod;
+
+    // -------------------------------------------------------------------------
+    // Placeholder API calls
+    // -------------------------------------------------------------------------
+    async function loadSalesSummary() {
+        // TODO: call /pos/api/cashregister/summary or similar
+    }
+
+    async function loadTopProducts() {
+        // TODO: call /pos/api/inventory/products?sort=sold
+    }
+
+    async function loadRecentSales() {
+        // TODO: call /pos/api/cashregister/recent
+    }
+
+    // -------------------------------------------------------------------------
+    // Init
+    // -------------------------------------------------------------------------
+    function init() {
+        if (!checkAuth()) return;
+
+        // Restore theme
+        try {
+            const saved = localStorage.getItem('nexus-theme');
+            if (saved === 'industrial' || saved === 'modern') {
+                setTheme(saved);
+            }
+        } catch(e) {}
+
+        loadSalesSummary();
+        loadTopProducts();
+        loadRecentSales();
+    }
+
+    document.addEventListener('DOMContentLoaded', init);
+
+    return { init, loadSalesSummary, loadTopProducts, loadRecentSales, setTheme };
+})();