feat(pos): add printer settings persistence for network printing

public/pos/epos-print.js

@@ -0,0 +1,28 @@
+// Network (ePOS-Print) thermal printing for Epson TM-series Ethernet
+// printers. Runs alongside the existing Web Bluetooth path in
+// receipt.html — the till picks a transport in Printer settings.
+//
+// The printer's ePOS-Print endpoint is served over HTTPS with a
+// self-signed cert and open CORS (`Access-Control-Allow-Origin: *`),
+// confirmed by direct testing against the shop's TM-T20II. Each till
+// device must visit `https://<printer-ip>` once in its browser and
+// accept the certificate warning before fetch() calls here succeed.
+window.EposPrint = (function () {
+  'use strict';
+
+  const SETTINGS_KEY = 'pos.printerSettings';
+
+  function getSettings() {
+    try {
+      return JSON.parse(localStorage.getItem(SETTINGS_KEY)) || { type: 'bluetooth', ip: '' };
+    } catch (e) {
+      return { type: 'bluetooth', ip: '' };
+    }
+  }
+
+  function setSettings(settings) {
+    localStorage.setItem(SETTINGS_KEY, JSON.stringify(settings));
+  }
+
+  return { getSettings, setSettings };
+})();