refactor: устранить дублирование кода (Go-хендлеры, JS-автокомплит)

Найдено статическим анализом (dupl/jscpd) + проверено вручную:

Go:
- appstate/path.go: ResolveDBPath/ResolveConfigPath → общий resolvePath()
- handlers/respond.go: дженерик BindJSON[T] для bind+422-ошибки
- article/generator.go: buildNetSegment/buildPSUSegment → buildProfileSegment()
- cmd/qfs/main.go (+respond.go): 8 повторяющихся switch{case errors.Is(...)}
  → respondByErrCase(c, err, errCase{...}, ...)

Frontend (index.html):
- 5 идентичных обработчиков клавиатурной навигации автокомплита
  → handleAutocompleteKeyGeneric(event, onSelect)
- 4 функции сборки нового элемента корзины из автокомплита
  → buildNewCartItem()/commitCartChange()

Также: PricingMarkup — единая точка правды для аплифт-коэффициента
в JS (render + export), с cross-reference комментариями к Go-константам
в export.go (defaultSaleMarkup/stockCompetitorMarkupFactor).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

internal/article/generator.go

@@ -260,17 +260,28 @@ func buildDiskSegment(items []models.ConfigItem, cats map[string]string) (string
 }
 
 func buildNetSegment(items []models.ConfigItem, cats map[string]string) (string, string) {
+	return buildProfileSegment(items, cats, GroupNET, parsePortSpeed, "UNKNET", "net_unknown")
+}
+
+func buildPSUSegment(items []models.ConfigItem, cats map[string]string) (string, string) {
+	return buildProfileSegment(items, cats, GroupPSU, parseWatts, "UNKPSU", "psu_unknown")
+}
+
+// buildProfileSegment groups items of the given category group by a profile token
+// parsed from their lot name (e.g. port speed, wattage rating), falling back to
+// unknownToken and warnCode when a lot's profile can't be determined.
+func buildProfileSegment(items []models.ConfigItem, cats map[string]string, group Group, parseProfile func(string) string, unknownToken, warnCode string) (string, string) {
 	groupQty := map[string]int{}
 	warn := ""
 	for _, it := range items {
-		group, ok := GroupForLotCategory(cats[it.LotName])
-		if !ok || group != GroupNET {
+		g, ok := GroupForLotCategory(cats[it.LotName])
+		if !ok || g != group {
 			continue
 		}
-		profile := parsePortSpeed(it.LotName)
+		profile := parseProfile(it.LotName)
 		if profile == "" {
-			profile = "UNKNET"
-			warn = "net_unknown"
+			profile = unknownToken
+			warn = warnCode
 		}
 		groupQty[profile] += it.Quantity
 	}
@@ -285,32 +296,6 @@ func buildNetSegment(items []models.ConfigItem, cats map[string]string) (string,
 	return strings.Join(parts, "+"), warn
 }
 
-func buildPSUSegment(items []models.ConfigItem, cats map[string]string) (string, string) {
-	groupQty := map[string]int{}
-	warn := ""
-	for _, it := range items {
-		group, ok := GroupForLotCategory(cats[it.LotName])
-		if !ok || group != GroupPSU {
-			continue
-		}
-		rating := parseWatts(it.LotName)
-		if rating == "" {
-			rating = "UNKPSU"
-			warn = "psu_unknown"
-		}
-		groupQty[rating] += it.Quantity
-	}
-	if len(groupQty) == 0 {
-		return "", ""
-	}
-	parts := make([]string, 0, len(groupQty))
-	for rating, qty := range groupQty {
-		parts = append(parts, fmt.Sprintf("%dx%s", qty, rating))
-	}
-	sort.Strings(parts)
-	return strings.Join(parts, "+"), warn
-}
-
 func normalizeModelToken(lotName string) string {
 	if idx := strings.Index(lotName, "_"); idx >= 0 && idx+1 < len(lotName) {
 		lotName = lotName[idx+1:]