Centralize daypart key canonicalization

internal/generatedtext/render_context.go

@@ -3,9 +3,7 @@ package generatedtext
 import (
 	"fmt"
 	"sort"
-	"strings"
 	"time"
-	"unicode"
 
 	"gitea.maximumdirect.net/eric/weatherreporter/internal/briefing"
 	"gitea.maximumdirect.net/eric/weatherreporter/internal/facts"
@@ -698,7 +696,7 @@ func orderedDaypartRows(dayparts *map[string]briefing.DerivedDaypartSummaryModul
 }
 
 func daypartModuleKeyCandidates(daypart forecast.DaypartSummary) []string {
-	key := normalizedDaypartKey(daypart.Name)
+	key := forecast.CanonicalDaypartKey(daypart.Name)
 	if key == "" {
 		key = "unnamed"
 	}
@@ -708,24 +706,6 @@ func daypartModuleKeyCandidates(daypart forecast.DaypartSummary) []string {
 	return []string{key, daypart.Period.Start.Format(timeutil.DateLayout) + "_" + key}
 }
 
-func normalizedDaypartKey(value string) string {
-	lower := strings.ToLower(strings.TrimSpace(value))
-	var out strings.Builder
-	lastUnderscore := false
-	for _, r := range lower {
-		if unicode.IsLetter(r) || unicode.IsDigit(r) {
-			out.WriteRune(r)
-			lastUnderscore = false
-			continue
-		}
-		if !lastUnderscore {
-			out.WriteByte('_')
-			lastUnderscore = true
-		}
-	}
-	return strings.Trim(out.String(), "_")
-}
-
 func locationName(metadata briefing.Metadata) string {
 	if metadata.Location != nil {
 		if metadata.Location.Name != "" && metadata.Location.Region != "" {