biblio-gui should resolve git-annex symlinks when serving files

Goal

(promoted from note)

Context

(see source note)

Prompt

Fix the issue described in /storage2/arash/projects/projio/docs/log/issue/issue-arash-20260326-142709-728239.md. Read it first, then implement the proposed fix.

Acceptance Criteria

• [ ]

Result

(pending)