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/features/room/RoomTombstone.tsx

@@ -36,7 +36,7 @@ export function RoomTombstone({ roomId, body, replacementRoomId }: RoomTombstone
         <Text size="T400">{body || 'This room has been replaced and is no longer active.'}</Text>
         {joinState.status === AsyncStatus.Error && (
           <Text style={{ color: color.Critical.Main }} size="T200">
-            {(joinState.error as any)?.message ?? 'Failed to join replacement room!'}
+            {(joinState.error as Error | undefined)?.message ?? 'Failed to join replacement room!'}
           </Text>
         )}
       </Box>