Improve search relevance and artist transliteration

services/api/internal/search/translit.go

@@ -6,6 +6,36 @@ import (
 	"unicode"
 )
 
+// Established spellings cannot always be derived letter by letter. Keep these
+// as whole-word alternatives, retaining the mechanical transliteration too.
+var pronunciationWords = map[string]string{"boulevard": "бульвар"}
+
+func TranslitVariants(s string) []string {
+	out := []string{}
+	if mechanical := Translit(s); mechanical != "" {
+		out = append(out, mechanical)
+	}
+	words := strings.Fields(strings.ToLower(s))
+	changed := false
+	for i, word := range words {
+		if spoken, ok := pronunciationWords[word]; ok {
+			words[i], changed = spoken, true
+		} else if translated := Translit(word); translated != "" {
+			words[i] = translated
+		}
+	}
+	if changed {
+		out = append(out, strings.Join(words, " "))
+	}
+	return out
+}
+
+func searchKey(s string) string {
+	return strings.Join(strings.FieldsFunc(strings.ToLower(s), func(r rune) bool {
+		return !unicode.IsLetter(r) && !unicode.IsDigit(r)
+	}), " ")
+}
+
 // Кириллица → латиница (упрощённая ГОСТ-подобная схема: «Кино» → «kino», «Щедрин» → «shchedrin»).
 var cyrToLat = map[rune]string{
 	'а': "a", 'б': "b", 'в': "v", 'г': "g", 'д': "d", 'е': "e", 'ё': "e", 'ж': "zh", 'з': "z", 'и': "i",