fix: various fixes in background jobs (#1362)

Co-authored-by: Elias Schneider <login@eliasschneider.com>

backend/internal/service/scheduler.go

@@ -0,0 +1,25 @@
+package service
+
+import (
+	"context"
+
+	backoff "github.com/cenkalti/backoff/v5"
+	"github.com/go-co-op/gocron/v2"
+)
+
+// RegisterJobOpts holds optional configuration for registering a scheduled job.
+type RegisterJobOpts struct {
+	// RunImmediately runs the job immediately after registration.
+	RunImmediately bool
+	// ExtraOptions are additional gocron job options.
+	ExtraOptions []gocron.JobOption
+	// BackOff is an optional backoff strategy. If non-nil, the job will be wrapped
+	// with automatic retry logic using the provided backoff on transient failures.
+	BackOff backoff.BackOff
+}
+
+// Scheduler is an interface for registering and managing background jobs.
+type Scheduler interface {
+	RegisterJob(ctx context.Context, name string, def gocron.JobDefinition, job func(ctx context.Context) error, opts RegisterJobOpts) error
+	RemoveJob(name string) error
+}