chore(lint): retire 19 explicit anys, ratchet to 49 warnings (#210)

Event handlers typed as React.MouseEvent, join errors as Error, the
service-worker session setter as strings, the UIA policy map and the
webkitAudioContext probe as narrow shapes. No behaviour change.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/plugins/call/CallEmbed.ts

@@ -368,7 +368,7 @@ export class CallEmbed {
     return this.listenEvent('preparing', callback);
   }
 
-  public onPreparingError(callback: (error: any) => void) {
+  public onPreparingError(callback: (error: unknown) => void) {
     return this.listenEvent('error:preparing', callback);
   }