feat(distlock): implement in-memory lease store

internal/distlock/store.go

@@ -0,0 +1,16 @@
+package distlock
+
+import (
+	"context"
+	"time"
+)
+
+// Store holds machine-local lease state and provides atomic operations over it.
+type Store interface {
+	// Acquire creates a lease when the resource does not have an unexpired lease.
+	Acquire(ctx context.Context, resource string, token []byte, ttl time.Duration) (bool, error)
+	// Renew extends an unexpired lease when its ownership token matches.
+	Renew(ctx context.Context, resource string, token []byte, ttl time.Duration) (bool, error)
+	// Release removes a lease when its ownership token matches.
+	Release(ctx context.Context, resource string, token []byte) (bool, error)
+}