feat(kavita): wait for OIDC to start

Previously we were running in to a race condition where OIDC wouldn't
start early enough, so kavita would load without it. As we have turned
off passwords entirely, this would cause the instance to be unusable

I've copied this wait code directly from our oauth2-proxy stuff, which
has the same problem. We should consider if there's a better way to do
this...

packetmix/systems/teal/kavita.nix

···
       ${pkgs.replace-secret}/bin/replace-secret '@OIDC_SECRET@' \
       ''${CREDENTIALS_DIRECTORY}/OIDC_SECRET \
       '${config.services.kavita.dataDir}/config/appsettings.json'
+
+      while [[ \"$(${pkgs.curl}/bin/curl -s -L https://idm.freshly.space/status)\" != \"true\" ]]; do sleep 5; done
     '';
     serviceConfig.LoadCredential = [ "OIDC_SECRET:/secrets/kavita/OIDC_SECRET" ];
   };