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/sw.ts

@@ -63,7 +63,7 @@ async function cleanupDeadClients() {
   });
 }
 
-function setSession(clientId: string, accessToken: any, baseUrl: any) {
+function setSession(clientId: string, accessToken: string, baseUrl: string) {
   if (typeof accessToken === 'string' && typeof baseUrl === 'string') {
     sessions.set(clientId, { accessToken, baseUrl });
   } else {