Euan Kemp 84ec657218 Update traffic policy example to work ...

The main issue was that we had a mix of spaces and tabs, and that makes
yaml parsers unhappy.

Before:
```
2025/06/18 08:40:32 INFO client session established
2025/06/18 08:40:32 The TrafficPolicy you provided is invalid: could not decode from string: The traffic policy was not able to be parsed:
yaml: line 4: found a tab character that violates indentation.
```

After:
```
2025/06/18 08:43:52 INFO client session established
2025/06/18 08:43:52 Endpoint online https://<random>.ngrok.app
```

I also plumbed in slog since otherwise there's no output on errors, which
is kinda unsettling.

2025-06-18 08:47:32 +00:00

..

main.go

Update traffic policy example to work

2025-06-18 08:47:32 +00:00