9a9ce9fd

Author: Michael Lynch <git@mtlynch.io>

Committer: Michael Lynch <mtlynch@noreply.codeberg.org>

Consolidate handler test helpers (#241)

Move shared handler test doubles and setup helpers into handlers/helpers_test.go.
Reuse the common fake session manager, media source, test server builders, and user insertion helper across auth and login tests.

Reviewed-on: https://codeberg.org/mtlynch/little-moments/pulls/241