Fix issue #4939: Move PostHog client key to config.json

frontend/public/config.json

@@ -1,4 +1,5 @@
 {
   "APP_MODE": "oss",
-  "GITHUB_CLIENT_ID": ""
+  "GITHUB_CLIENT_ID": "",
+  "POSTHOG_CLIENT_KEY": "phc_3ESMmY9SgqEAGBB6sMGK5ayYHkeUuknH2vP6FmWH9RA"
 }

frontend/src/entry.client.tsx

@@ -15,10 +15,14 @@ import store from "./store";
 
 function PosthogInit() {
   React.useEffect(() => {
-    posthog.init("phc_3ESMmY9SgqEAGBB6sMGK5ayYHkeUuknH2vP6FmWH9RA", {
-      api_host: "https://us.i.posthog.com",
-      person_profiles: "identified_only",
-    });
+    fetch("/config.json")
+      .then((response) => response.json())
+      .then((config) => {
+        posthog.init(config.POSTHOG_CLIENT_KEY, {
+          api_host: "https://us.i.posthog.com",
+          person_profiles: "identified_only",
+        });
+      });
   }, []);
 
   return null;