refactor: replace standard log with zap logger and optimize code patterns

- Migrate all log.Printf/log.Println calls to structured zap logging
- Use cmp.Or for cleaner default value handling
- Replace manual loops with slices.ContainsFunc/IndexFunc
- Add batch query methods (IsLikedBatch, IsFavoritedBatch) to solve N+1 problem
- Update JSON tags from omitempty to omitzero for numeric fields
- Use errgroup-style wg.Go for worker goroutines
- Remove duplicate casbin/v2 dependency (keeping v3)
- Add plans/ to gitignore

internal/service/schedule_service.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"errors"
 	"regexp"
+	"slices"
 	"sort"
 	"strings"
 
@@ -188,12 +189,7 @@ func normalizeWeeks(source []int) []int {
 }
 
 func containsWeek(weeks []int, target int) bool {
-	for _, week := range weeks {
-		if week == target {
-			return true
-		}
-	}
-	return false
+	return slices.Contains(weeks, target)
 }
 
 func normalizeHexColor(color string) string {