Add Lucide icons, web server, and settings page cleanup

- Replace emoji icons with Lucide SVG icons (moon, sun, settings, x, upload, rotate-ccw, trash-2, save)
- Add Node.js dev server on port 3010 (server.js + npm run serve)
- Redesign settings modal: tabbed layout, styled form fields, Save/Cancel footer
- Fix dark mode: btn-danger hover now uses rgba instead of hardcoded light pink
- Fix stale pendingBranding: history item click now calls revertAndClose()
- Collapse branding header when no name/logo is set
- Move density row inline style to .density-info CSS class
- Normalise all innerText to textContent

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

server.js

@@ -0,0 +1,34 @@
+const http = require('http');
+const fs = require('fs');
+const path = require('path');
+
+const PORT = 3010;
+
+const mimeTypes = {
+    '.html': 'text/html',
+    '.js':   'application/javascript',
+    '.css':  'text/css',
+    '.png':  'image/png',
+    '.ico':  'image/x-icon',
+    '.json': 'application/json',
+};
+
+const server = http.createServer((req, res) => {
+    const filePath = path.join(__dirname, req.url === '/' ? 'index.html' : req.url);
+    const ext = path.extname(filePath);
+    const contentType = mimeTypes[ext] || 'application/octet-stream';
+
+    fs.readFile(filePath, (err, data) => {
+        if (err) {
+            res.writeHead(404, { 'Content-Type': 'text/plain' });
+            res.end('404 Not Found');
+            return;
+        }
+        res.writeHead(200, { 'Content-Type': contentType });
+        res.end(data);
+    });
+});
+
+server.listen(PORT, () => {
+    console.log(`Freight Calculator Pro running at http://localhost:${PORT}`);
+});