fix(desktop): key-based React remount for workspace switching (#415)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

desktop/src/shared/lib/mediaUrl.ts

@@ -70,6 +70,16 @@ if (typeof window !== "undefined") {
   portPromise = fetchProxyPort();
 }
 
+/**
+ * Reset module-level caches so the next render re-fetches the proxy port
+ * and relay origin for the new workspace.
+ */
+export function resetMediaCaches(): void {
+  cachedPort = null;
+  portPromise = null;
+  cachedRelayOrigin = null;
+}
+
 /**
  * If `url` is a Blossom media URL hosted on the Sprout relay, rewrite it
  * to go through the localhost streaming proxy. External Blossom URLs and