feat(monospace): add get/set IPC handlers with safe validation

src/main/ipc/monospace-handlers.js

@@ -0,0 +1,29 @@
+'use strict';
+
+const { ipcMain } = require('electron');
+const store = require('../store');
+const { safeMonospaceSettings, DEFAULT_SETTINGS } = require('../settings/monospaceSettings');
+
+function readCurrent() {
+  return {
+    monospaceFont: store.get('monospaceFont', DEFAULT_SETTINGS.monospaceFont),
+    monospaceLigatures: store.get('monospaceLigatures', DEFAULT_SETTINGS.monospaceLigatures),
+  };
+}
+
+function register() {
+  ipcMain.handle('get-monospace-settings', () => readCurrent());
+
+  ipcMain.handle('set-monospace-settings', (_event, partial) => {
+    const safe = safeMonospaceSettings(partial || {});
+    if (Object.prototype.hasOwnProperty.call(partial || {}, 'monospaceFont')) {
+      store.set('monospaceFont', safe.monospaceFont);
+    }
+    if (Object.prototype.hasOwnProperty.call(partial || {}, 'monospaceLigatures')) {
+      store.set('monospaceLigatures', safe.monospaceLigatures);
+    }
+    return readCurrent();
+  });
+}
+
+module.exports = { register, readCurrent };