Explicit mouse URL test uses a different GTF from CI and an unformatted transcript URL #563

Current CI installs the full GRCm38 release-95 GTF (Mus_musculus.GRCm38.95.chr_patch_hapl_scaff.gtf.gz), but tests/test_mouse.py constructs its explicit-URL genome with the older primary-assembly filename. A warm workstation hides this; a clean CI job tries FTP during the test and fails because that other GTF database was never indexed. The explicit transcript URL also contains a literal unexpanded release-%d.

Observed on PR #562, job 109480841995: 2,993 tests passed and only test_specific_variant_mouse_with_explicit_urls failed. Use canonical HTTPS URLs and the same full-GTF filename as the explicitly installed release; format the transcript release. Keep the exact protein-effect assertions.