Configure analytics explicitly instead of discovering it

PosthogAnalytics read its own configuration out of the environment on
first use: the URL parameters, config.json, and the widget global. An
embedded Element Call has none of those to offer, and analytics that
configure themselves cannot be switched off by a host that does its own
reporting.

Take an AnalyticsConfig through PosthogAnalytics.configure() instead,
called from the initializer once the config has loaded. Unconfigured
analytics stay off.

Note the two halves of that config are decided differently, and have to
be: where the credentials come from depends on the package, but who owns
the user's analytics identity depends on how Element Call is running,
since the full package can be used as a widget too.

Drop the widget check around cryptoVersion, which never did anything —
widget mode never initialises crypto, so getCrypto() is already undefined
there.

Move the tests covering which package reads which credential source onto
analyticsConfigFromEnvironment, where that decision now lives.

src/initializer.tsx

@@ -34,6 +34,10 @@ import { platform } from "./Platform";
 import { isFailure } from "./utils/fetch";
 import { initializeWidget } from "./widget";
 import { enableExtendedLivekitLogs } from "./settings/settings.ts";
+import {
+  type AnalyticsConfig,
+  PosthogAnalytics,
+} from "./analytics/PosthogAnalytics.ts";
 import { i18n } from "./utils/i18n.ts";
 
 // This generates a map of locale names to their URL (based on import.meta.url), which looks like this:
@@ -98,6 +102,36 @@ const Backend = {
   },
 } satisfies BackendModule;
 
+/**
+ * Where analytics reporting is configured from.
+ *
+ * Note the two halves are decided differently, and deliberately so. *Where the
+ * PostHog credentials come from* depends on the package: an embedder passes
+ * them in through the URL because it is responsible for its own users'
+ * telemetry, whereas a standalone deployment is configured by whoever operates
+ * it. *Who owns the user's analytics identity*, on the other hand, depends on
+ * how Element Call is actually running right now — the full package can be used
+ * as a widget too.
+ */
+// Exported for testing
+export function analyticsConfigFromEnvironment(): AnalyticsConfig {
+  const { posthogApiKey, posthogApiHost, posthogUserId, isWidget } =
+    getUrlParams();
+  return {
+    matrixBackend: isWidget ? "embedded" : "jssdk",
+    hostAnalyticsId: posthogUserId,
+    ...(import.meta.env.VITE_PACKAGE === "embedded"
+      ? {
+          apiKey: posthogApiKey ?? undefined,
+          apiHost: posthogApiHost ?? undefined,
+        }
+      : {
+          apiKey: Config.get().posthog?.api_key,
+          apiHost: Config.get().posthog?.api_host,
+        }),
+  };
+}
+
 enum LoadState {
   None,
   Loading,
@@ -241,6 +275,7 @@ export class Initializer {
       Config.init().then(
         () => {
           seedSettingsFromConfig(Config.get().media_quality);
+          PosthogAnalytics.configure(analyticsConfigFromEnvironment());
           this.loadStates.config = LoadState.Loaded;
           this.initStep(resolve);
         },