fix(jig): show correct error messages when fetching registry base path

[technillogue]

use Together.get instead of Together._client.get so that registry errors are handled correctly

old:

$ together beta jig deploy
Jig: Failed
Jig: Failed to get registry path (HTTP 403)
$ TOGETHER_API_KEY=asdf together beta jig deploy
Jig: Failed
Jig: Failed to get registry path (HTTP 401)

new:

$ together beta jig deploy
Jig: Failed
Jig: Together Dedicated Container Inference is an enterprise feature. Please contact support or your account representative.
$ TOGETHER_API_KEY=asdf together beta jig deploy
Jig: Failed
Jig: Invalid or missing API key. Set TOGETHER_API_KEY or use --api-key.