feat(enterprise): add shard management commands (#168)

- List shards with optional filtering by node, database, or role
- Get individual shard details
- Failover operations (manual and automatic)
- Migrate shards between nodes
- View shard statistics (real-time and historical)
- Comprehensive mdBook documentation
- Support for stdin input via '-' flag

Author: joshrotenberg

crates/redisctl/src/cli.rs

@@ -1024,6 +1024,10 @@ pub enum EnterpriseCommands {
     #[command(subcommand)]
     Workflow(EnterpriseWorkflowCommands),
 
+    /// Shard management operations
+    #[command(subcommand)]
+    Shard(crate::commands::enterprise::shard::ShardCommands),
+
     /// Statistics and metrics operations
     #[command(subcommand)]
     Stats(EnterpriseStatsCommands),

crates/redisctl/src/commands/enterprise/mod.rs

@@ -19,5 +19,6 @@ pub mod node;
 pub mod node_impl;
 pub mod rbac;
 pub mod rbac_impl;
+pub mod shard;
 pub mod stats;
 pub mod utils;