feat(distlock): implement distributed Locker based on Redlock algorithm

pkg/distlock/doc.go

@@ -1,5 +1,10 @@
 // Package distlock provides distributed, automatically renewed leases across independent nodes.
 //
+// Its quorum and lease semantics are based on the Redlock algorithm described at
+// https://redis.io/docs/latest/develop/clients/patterns/distributed-locks/. The core package is independent of storage
+// and network transport and does not require Redis. Applications that communicate with remote nodes over gRPC can use
+// the grpc subpackage to expose and call node-local lease operations.
+//
 // A Cluster must return every node in the lock group, including temporarily unavailable nodes, because every node
 // counts toward quorum. Changing the node set is unsafe if a new quorum can be disjoint from an earlier quorum while
 // leases acquired from the earlier node set may still be valid. Callers must stop protected work when the context