📦 Improve logger error messages to simplify investigate on error

[andrew-demb]

Before:

$ docker run --rm -p 8080:8080 -e CF_API_TOKEN=${CF_API_TOKEN} -e CF_ZONES=${CF_ZONES} ghcr.io/lablabs/cloudflare_exporter
time="2025-03-16 14:55:04" level=info msg="Beginning to serve metrics on :8080/metrics"
time="2025-03-16 14:55:05" level=info msg="Filtering zone: ...hidden..."
time="2025-03-16 14:55:09" level=fatal msg="Authentication error (10000)"

After:

$ docker run --rm -p 8080:8080 -e CF_API_TOKEN=${CF_API_TOKEN} -e CF_ZONES=${CF_ZONES} ghcr.io/lablabs/cloudflare_exporter 
time="2025-03-16 14:51:17" level=info msg="Beginning to serve metrics on :8080/metrics"
time="2025-03-16 14:51:19" level=info msg="Filtering zone: ...hidden..."
time="2025-03-16 14:51:21" level=fatal msg="failed to fetch firewall rules: Authentication error (10000)"

[danila-terekhov]

Great pr merge this pls)