chore: downgrade bbolt to v1.3.7 and add cron schedule comments

Author: Hell1213

backend/go.mod

@@ -1,12 +1,14 @@
 module ccsync_backend
 
-go 1.23
+go 1.19
 
 require (
 	github.com/charmbracelet/log v0.4.2
 	github.com/gorilla/sessions v1.2.2
+	github.com/robfig/cron/v3 v3.0.1
 	github.com/swaggo/http-swagger v1.3.4
 	github.com/swaggo/swag v1.16.3
+	go.etcd.io/bbolt v1.3.7
 	golang.org/x/oauth2 v0.20.0
 )
 
@@ -33,10 +35,8 @@ require (
 	github.com/muesli/termenv v0.16.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
-	github.com/robfig/cron/v3 v3.0.1 // indirect
 	github.com/swaggo/files v0.0.0-20220610200504-28940afbdbfe // indirect
 	github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e // indirect
-	go.etcd.io/bbolt v1.4.3 // indirect
 	golang.org/x/exp v0.0.0-20231006140011-7918f672742d // indirect
 	golang.org/x/net v0.17.0 // indirect
 	golang.org/x/sys v0.30.0 // indirect

backend/go.sum

@@ -85,8 +85,8 @@ github.com/swaggo/swag v1.16.3 h1:PnCYjPCah8FK4I26l2F/KQ4yz3sILcVUN3cTlBFA9Pg=
 github.com/swaggo/swag v1.16.3/go.mod h1:DImHIuOFXKpMFAQjcC7FG4m3Dg4+QuUgUzJmKjI/gRk=
 github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e h1:JVG44RsyaB9T2KIHavMF/ppJZNG9ZpyihvCd0w101no=
 github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e/go.mod h1:RbqR21r5mrJuqunuUZ/Dhy/avygyECGrLceyNeo4LiM=
-go.etcd.io/bbolt v1.4.3 h1:dEadXpI6G79deX5prL3QRNP6JB8UxVkqo4UPnHaNXJo=
-go.etcd.io/bbolt v1.4.3/go.mod h1:tKQlpPaYCVFctUIgFKFnAlvbmB3tpy1vkTnDWohtc0E=
+go.etcd.io/bbolt v1.3.7 h1:j+zJOnnEjF/kyHlDDgGnVL/AIqIJPq8UoB2GSNfkUfQ=
+go.etcd.io/bbolt v1.3.7/go.mod h1:N9Mkw9X8x5fupy0IKsmuqVtoGDyxsaDlbk4Rd05IAQw=
 golang.org/x/exp v0.0.0-20231006140011-7918f672742d h1:jtJma62tbqLibJ5sFQz8bKtEM8rJBtfilJ2qTU199MI=
 golang.org/x/exp v0.0.0-20231006140011-7918f672742d/go.mod h1:ldy0pHrwJyGW56pPQzzkH36rKxoZW1tw7ZJpeKx+hdo=
 golang.org/x/mod v0.13.0 h1:I/DsJXRlw/8l/0c24sM9yb0T4z9liZTduXvdAWYiysY=

backend/utils/maintenance_worker.go

@@ -20,11 +20,21 @@ func NewMaintenanceWorker(queue PersistentJobQueue) *MaintenanceWorker {
 }
 
 func (mw *MaintenanceWorker) Start() error {
+	// CLEANUP_CRON_SCHEDULE: Cron expression for cleanup schedule
+	// Format: "minute hour day month weekday"
+	// Examples:
+	//   "0 0 * * *"   - Daily at midnight (default)
+	//   "0 */6 * * *" - Every 6 hours
+	//   "0 2 * * *"   - Daily at 2 AM
+	//   "0 0 * * 0"   - Weekly on Sunday
 	schedule := os.Getenv("CLEANUP_CRON_SCHEDULE")
 	if schedule == "" {
 		schedule = "0 0 * * *"
 	}
 
+	// CLEANUP_RETENTION_DAYS: Number of days to keep completed/failed job logs
+	// Default: 7 days
+	// Set to higher value to keep logs longer, lower to cleanup more frequently
 	retentionDaysStr := os.Getenv("CLEANUP_RETENTION_DAYS")
 	retentionDays := 7
 	if retentionDaysStr != "" {