feat(operator): add queue-operator CRD reconciler with shard split/drain

Reconciles Queue CRs into Kafka topics + Redis shard-map/queue-meta state:
creates shard-0 on first reconcile, splits a shard's hash range into two
children once its split threshold is crossed, drains and closes a parent
shard once its consumer group has fully caught up and its retention
window has elapsed, and tears down every shard's topic + Redis state on
deletion. Includes the manager entrypoint (cmd/queue-operator) and RBAC.

internal/operator/fake_admin.go

@@ -0,0 +1,71 @@
+package operator
+
+import (
+	"context"
+	"sync"
+
+	"github.com/rockliang/kafka-management-service/internal/kafka"
+)
+
+// fakeAdmin is an in-memory TopicAdmin for reconciler tests — avoids needing
+// a real Kafka cluster (or envtest's apiserver binaries, which aren't
+// available in this environment) just to exercise reconcile logic.
+type fakeAdmin struct {
+	mu         sync.Mutex
+	topics     map[string]kafka.TopicConfig
+	offsetSums map[string]int64
+	lag        map[string]int64 // keyed by group+"/"+topic
+}
+
+func newFakeAdmin() *fakeAdmin {
+	return &fakeAdmin{
+		topics:     map[string]kafka.TopicConfig{},
+		offsetSums: map[string]int64{},
+		lag:        map[string]int64{},
+	}
+}
+
+func (f *fakeAdmin) CreateTopic(_ context.Context, topic string, cfg kafka.TopicConfig) error {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	f.topics[topic] = cfg
+	return nil
+}
+
+func (f *fakeAdmin) DeleteTopic(_ context.Context, topic string) error {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	delete(f.topics, topic)
+	return nil
+}
+
+func (f *fakeAdmin) LogEndOffsetSum(_ context.Context, topic string) (int64, error) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	return f.offsetSums[topic], nil
+}
+
+func (f *fakeAdmin) ConsumerLag(_ context.Context, group, topic string) (int64, error) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	return f.lag[group+"/"+topic], nil
+}
+
+func (f *fakeAdmin) setOffsetSum(topic string, v int64) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	f.offsetSums[topic] = v
+}
+
+func (f *fakeAdmin) setLag(group, topic string, v int64) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	f.lag[group+"/"+topic] = v
+}
+
+func (f *fakeAdmin) hasTopic(topic string) bool {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	_, ok := f.topics[topic]
+	return ok
+}