[Bug]: BroadcastChannel Loses Messages On Update

### Problem description

Whenever you update your deno code, BroadcastChannel on previous versions no longer receives any messages.

### Steps to reproduce

1. Use BroadcastChannels
2. Connect to an SSE/WS endpoint
3. Update the code
4. See that the old connection will never get any messages from BroadcastChannel again

### Expected behavior

While it maybe does make sense that there could be breaking changes made between versions maybe instead of no longer sending messages the old isolate should be killed and all connections dropped instead of no longer sending messages to it.

### Environment

_No response_

### Possible solution

- Kill old isolates / close out connections for websockets/sse
- Keep sending messages to old isolates also, expect dev to handle errors of breaking changes by closing sockets and reconnecting

### Additional context

_No response_

No files, tests, or entry points are named. Start by tracing BroadcastChannel delivery across updated isolates and the SSE/WebSocket connection lifecycle. Done means old connections are either closed when their isolates are replaced or continue receiving messages without silently losing them.

Written by the indexing model from the issue text.