7a7ef76c

Return ErrUnregisteredEmail from NewSender instead of empty entry

NewSender now returns a magiclogin.ErrUnregisteredEmail error for
unknown addresses instead of silently returning an empty token entry.
Callers handle the error explicitly and redirect to /login/check-email.

Inline LoginConfirmPath into the dev creator and remove login_redirect.go.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Agent Instructions

Each run corresponds to one flake attribute. Click a run for its logs and status.

Example: https://nix-ci.com/cb:mtlynch:little-moments/redirect-dev/7a7ef76c6450ad85b1c4965ca8c94a1f4a0bda57/b3900f17-a05f-4742-b56d-458b22b83bfb

Wait for suite to complete:

curl --netrc -N https://nix-ci.com/cb:mtlynch:little-moments/redirect-dev/7a7ef76c6450ad85b1c4965ca8c94a1f4a0bda57/wait

This page is also available in machine-friendly formats. Request one with the Accept header:

• curl --netrc -H 'Accept: application/json' https://nix-ci.com/cb:mtlynch:little-moments/redirect-dev/7a7ef76c6450ad85b1c4965ca8c94a1f4a0bda57
• curl --netrc -H 'Accept: text/markdown' https://nix-ci.com/cb:mtlynch:little-moments/redirect-dev/7a7ef76c6450ad85b1c4965ca8c94a1f4a0bda57

For more instructions, fetch https://nix-ci.com/instructions .