feat: autotag scoring overhaul, dump-based explore index, and lyrics search

Consolidates in-progress work across autotag, explore, and library:

- autotag: beets/Picard-informed scoring engine — ID-first matching, VA
  handling, recommendation tiers, and a merged distance/rank cascade, with
  an eval harness for regression tracking.
- explore: offline MusicBrainz dump import/incremental refresh replaces the
  legacy tier crawl; index-first local search with fuzzy matching and a
  dedicated ranker; disk-free guards for dump downloads.
- library: artist-credit extraction and matching.
- lyrics: owned-library lyric search (FTS) with LRCLIB backfill.

Also: rewrite README to be user-focused, and migrate upstream to
git.ljones.me/yonlu/yellowjacket.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

main.go

@@ -14,6 +14,7 @@ import (
 
 	"yellowjacket/backend"
 	"yellowjacket/backend/assets"
+	"yellowjacket/backend/config"
 	"yellowjacket/backend/logging"
 	"yellowjacket/backend/profiling"
 	"yellowjacket/internal/dev"
@@ -86,8 +87,8 @@ func main() {
 		OnBeforeClose:    yjApp.OnBeforeClose,
 		OnShutdown:       yjApp.OnShutdown,
 		Bind:             yjApp.FEBindings,
-		MinWidth:         512,
-		MinHeight:        384,
+		MinWidth:         config.MinWidth,
+		MinHeight:        config.MinHeight,
 		MaxWidth:         0,
 		MaxHeight:        0,
 		Linux: &linux.Options{