Make job alerts available to guest

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**would be cool to have job alerts available not only to loggedin users.** Just like recently with submit resume.

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The issue names no files, entry points, or tests. Locate the job-alert implementation and its logged-in-user restriction, then compare it with the recently added guest support for submit resume. Done should mean guests can use job alerts while existing logged-in behavior remains intact, with coverage for both access paths.

Written by the indexing model from the issue text.