Make Webview Zoom Changeable from Home Assistant (#52)

* Add Page Zoom Control

Adds MQTT discovery for a "Page Zoom" input to control the `WEBVIEW.viewZoom` parameter.

The MQTT value has been configured to be in % which is then converted to a scale factor when assigned or read from `WEBVIEW.viewZoom`.

* Correct Type for page_zoom publishConfig

Accidentally replaced "number" with "zoom" when changing paramters.

* Add updateZoom Functionality to webview

Add a setter function for the viewZoom property that updates the zoom factor for all views when the property is changed.

js/webview.js

@@ -38,7 +38,15 @@ const init = async () => {
 
   // Init global properties
   WEBVIEW.viewUrls = urls;
-  WEBVIEW.viewZoom = zoom;
+  Object.defineProperty(WEBVIEW, "viewZoom", {
+    get() {
+      return this._viewZoom || zoom;
+    },
+    set(v) {
+      this._viewZoom = Math.max(0, v);
+      updateZoom();
+    },
+  });
   WEBVIEW.viewTheme = theme;
   WEBVIEW.widgetTheme = theme;
   WEBVIEW.widgetEnabled = widget;
@@ -315,6 +323,17 @@ const resizeView = () => {
   }
 };
 
+/**
+ * Updates zoom level for all webviews.
+ */
+const updateZoom = () => {
+  // And apply to all views
+  WEBVIEW.views.forEach((view) => {
+    view.webContents.setZoomFactor(WEBVIEW.viewZoom);
+  });
+
+};
+
 /**
  * Register window events and handler.
  */