feat: serve audio as local Hugo page resources instead of Jellyfin

Download all 20 track MP3s from Jellyfin and store them as page bundle
resources (track.mp3). Update templates to use .Resources.GetMatch
instead of .Params.audio, removing external API key dependencies.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

content/tracks/changed-her-mind-again/index.md

@@ -4,7 +4,6 @@ date: 2025-09-10
 draft: false
 description: "Again..."
 
-audio: "https://jellyfin.media.pivoine.art/Items/ebd4e9f45b9dda1cada560af5e6cb7a8/Download?api_key=64d0a008577f49a4aa276d4bbe5c5d60"
 duration: "4:07"
 
 artist: "Valknar"