feat(config,migrations): replace env.cluster_name with migrations.table; add replicated cluster override

[StopMakingThatBigFace]

Release Notes

Highlights

• New migrations table configuration block: migrations.table { ... }.
• Removed reliance on env.cluster_name for migrations table creation.
• Added optional migrations.table.cluster_name as an explicit ON CLUSTER override.
• Added clear runtime logging when the migrations table is created.

Configuration Changes

• New table config structure:
  • migrations.table.name
  • migrations.table.is_replicated
  • migrations.table.cluster_name (optional)
  • migrations.table.replication_path (optional)
• Replicated mode is now enabled automatically if either of these is set:
  • migrations.table.replication_path
  • migrations.table.cluster_name

Cluster Resolution Behavior

• If migrations.table.cluster_name is provided, it is used for ON CLUSTER.
• If not provided, clisma auto-detects cluster from system.clusters.
• If multiple non-default clusters are detected and no override is set, clisma fails with a clear error asking to set migrations.table.cluster_name.

Template Variables

• migrations.table.cluster_name is exposed to templates as {{cluster_name}} (when set).