releaseparser: adopt fixed positional model, auto-detect catalogues, add GB doc-blocks

Parse releases with an explicit fixed positional model and document the
whole logic in British English doc-blocks.

Model:
- [0]=Artist, [1]=Title are fixed and never matched against dictionaries,
  so titles like "Split"/"Demo"/"De" are never eaten.
- [len-1]=Group is always read from the line, not from the query key.
- [len-2]=Year when it is a 4-digit 19xx|20xx token; otherwise the slot is
  resolved as a middle-zone token (e.g. FLAC still picked up as format).
- The middle zone is resolved via case-insensitive dictionaries in the order
  format -> source -> bit-depth -> resolution -> edition -> language ->
  catalogue number. Position within the zone is irrelevant.

Catalogue numbers:
- Any "(...)" token in the middle zone is a catalogue number regardless of
  content (digits, roman numerals, dots, underscores, mixed case). Removed
  the hasDigit requirement and character whitelist that rejected real
  catalogues like (DYN.3140-2) and (GOWP_DCCCLXXXIX).
- Splitting never breaks tokens inside parentheses.

Case handling: lookups are case-insensitive; stored values keep their
original case from the line.

Documentation: replaced Ukrainian comments in parser.go and analyzer.go with
British-English doc-blocks describing the model, tail resolution order,
catalogue rule and confidence scoring.

Tests:
- Add TestParseCatalogNumberWithDotAndRoman for (DYN.3140-2)/(GOWP_DCCCLXXXIX).
- Update case-insensitive, split-title, no-year and language expectations.
- go build, go vet and go test all pass.

internal/releaseparser/types.go

@@ -9,6 +9,7 @@ type GroupProfile struct {
 	ResolutionTokens  map[string]bool
 	LanguageMarkers   map[string]bool
 	EditionTokens     map[string]bool
+	CommentTokens     map[string]bool
 }
 
 type ParsedRelease struct {
@@ -18,6 +19,7 @@ type ParsedRelease struct {
 	BitDepth      string
 	Resolution    string
 	Comment       string
+	CatalogNo     string
 	Source        string
 	Format        string
 	Language      string
@@ -44,6 +46,8 @@ type GroupStats struct {
 	ResolutionDistribution map[string]int
 	LanguageDistribution   map[string]int
 	EditionDistribution    map[string]int
+	CommentDistribution    map[string]int
 	UnknownTokens          []UnknownTokenStats
+	WarningStats           []UnknownTokenStats
 	AvgConfidence          float64
 }