Plakar API should not make external calls if not logged in

[brmzkw]

When internet is down:

 go build -v . && ./plakar at ./toto ui -cors -addr 0.0.0.0:30112 -no-spawn -no-auth
launching webUI at http://0.0.0.0:30112
2025/12/24 14:18:40 Unknown error encountered while serving /api/proxy/v1/account/me: Get "https://api.plakar.io/v1/account/me": dial tcp: lookup api.plakar.io: no such host
2025/12/24 14:18:40 Unknown error encountered while serving /api/proxy/v1/reporting/reports?repository_id=a3dc967d-51a3-40ad-9a7a-aebfa4db87dc&reverse=1&offset=0&limit=5: Get "https://api.plakar.io/v1/reporting/reports?repository_id=a3dc967d-51a3-40ad-9a7a-aebfa4db87dc&reverse=1&offset=0&limit=5": dial tcp: lookup api.plakar.io: no such host
2025/12/24 14:18:40 Unknown error encountered while serving /api/proxy/v1/account/notifications?offset=0&limit=50&repository_id=a3dc967d-51a3-40ad-9a7a-aebfa4db87dc&reverse=1&status=unread: Get "https://api.plakar.io/v1/account/notifications?offset=0&limit=50&repository_id=a3dc967d-51a3-40ad-9a7a-aebfa4db87dc&reverse=1&status=unread": dial tcp: lookup api.plakar.io: no such host
[...]

If the user is not logged in, we should not attempt to make external calls.