fix: use _gff_gene_name_attribute in _transcript_to_parent_name (#883)

[31puneet]

Description

Fixes #883. _transcript_to_parent_name() in genome_features.py hardcodes "Name" when looking up gene names, but af1/adir1 use "Note".

Changes Made

- return rec_parent.get("Name", parent_id)
+ return rec_parent.get(self._gff_gene_name_attribute, parent_id)

Before (af1/adir1)

AFUN007757-RA SNP frequencies

Gene name missing — falls back to gene ID.

After (af1/adir1)

AFUN007757-RA (epoxide hydrolase) SNP frequencies

Gene name correctly retrieved from "Note" attribute.

Impact

• Fixes gene name display in 4 functions: snp_allele_frequencies(), aa_allele_frequencies(), snp_allele_frequencies_advanced(), aa_allele_frequencies_advanced()
• No breaking changes — ag3 behavior unchanged
• All existing tests pass

[jonbrenas]

LGTM