feat(wfe-valkey): add Valkey provider for locks, queues, and lifecycle events

ValkeyLockProvider: SET NX EX for acquisition, Lua script for safe release.
ValkeyQueueProvider: LPUSH/RPOP for FIFO queues.
ValkeyLifecyclePublisher: PUBLISH to per-instance and global channels.

Connections obtained once during construction (no per-operation TCP handshakes).

wfe-valkey/src/lib.rs

@@ -0,0 +1,7 @@
+pub mod lifecycle;
+pub mod lock;
+pub mod queue;
+
+pub use lifecycle::ValkeyLifecyclePublisher;
+pub use lock::ValkeyLockProvider;
+pub use queue::ValkeyQueueProvider;