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/lifecycle.rs

@@ -0,0 +1,55 @@
+use async_trait::async_trait;
+use wfe_core::models::LifecycleEvent;
+use wfe_core::traits::LifecyclePublisher;
+
+pub struct ValkeyLifecyclePublisher {
+    conn: redis::aio::MultiplexedConnection,
+    prefix: String,
+}
+
+impl ValkeyLifecyclePublisher {
+    pub async fn new(redis_url: &str, prefix: &str) -> wfe_core::Result<Self> {
+        let client = redis::Client::open(redis_url)
+            .map_err(|e| wfe_core::WfeError::Persistence(e.to_string()))?;
+        let conn = client
+            .get_multiplexed_tokio_connection()
+            .await
+            .map_err(|e| wfe_core::WfeError::Persistence(e.to_string()))?;
+        Ok(Self {
+            conn,
+            prefix: prefix.to_string(),
+        })
+    }
+}
+
+#[async_trait]
+impl LifecyclePublisher for ValkeyLifecyclePublisher {
+    async fn publish(&self, event: LifecycleEvent) -> wfe_core::Result<()> {
+        let mut conn = self.conn.clone();
+        let json = serde_json::to_string(&event)?;
+
+        let instance_channel = format!(
+            "{}:lifecycle:{}",
+            self.prefix, event.workflow_instance_id
+        );
+        let all_channel = format!("{}:lifecycle:all", self.prefix);
+
+        // Publish to the instance-specific channel.
+        redis::cmd("PUBLISH")
+            .arg(&instance_channel)
+            .arg(&json)
+            .query_async::<i64>(&mut conn)
+            .await
+            .map_err(|e| wfe_core::WfeError::Persistence(e.to_string()))?;
+
+        // Publish to the global "all" channel.
+        redis::cmd("PUBLISH")
+            .arg(&all_channel)
+            .arg(&json)
+            .query_async::<i64>(&mut conn)
+            .await
+            .map_err(|e| wfe_core::WfeError::Persistence(e.to_string()))?;
+
+        Ok(())
+    }
+}