add first commit

background.js

@@ -0,0 +1,11 @@
+chrome.runtime.onInstalled.addListener(() => {
+    chrome.storage.local.get("replacements", (data) => {
+      if (!data.replacements) {
+        fetch(chrome.runtime.getURL("replacements.json"))
+          .then((response) => response.json())
+          .then((json) => {
+            chrome.storage.local.set({ replacements: json });
+          });
+      }
+    });
+  });