fix(model): Add MigrationOptions field to ChDestination

Add ChSinkMigrationOptions struct and MigrationOptions field to
ChDestination to support automatic column addition during schema
migration. This fixes the CI build failure in evolution tests.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: bvt123

pkg/providers/clickhouse/model/model_ch_destination.go

@@ -33,6 +33,11 @@ type ClickHouseColumnValueToShardName struct {
 	ShardName   string
 }
 
+// ChSinkMigrationOptions controls schema migration behavior
+type ChSinkMigrationOptions struct {
+	AddNewColumns bool `json:"AddNewColumns"` // When true, automatically add new columns from source to target
+}
+
 var (
 	_ model.Destination          = (*ChDestination)(nil)
 	_ model.Describable          = (*ChDestination)(nil)
@@ -53,9 +58,10 @@ type ChDestination struct {
 	HTTPPort                  int    `log:"true"`
 	NativePort                int    `log:"true"`
 	TTL                       string `log:"true"`
-	InferSchema               bool   `log:"true"`
-	ConnectionID              string `log:"true"`
-	IsSchemaMigrationDisabled bool   `log:"true"`
+	InferSchema               bool                    `log:"true"`
+	MigrationOptions          *ChSinkMigrationOptions `log:"true"`
+	ConnectionID              string                  `log:"true"`
+	IsSchemaMigrationDisabled bool                    `log:"true"`
 	// ForceJSONMode forces JSON protocol at sink:
 	// - allows upload records without 'required'-fields, clickhouse fills them via defaults.
 	//         BUT IF THEY ARE 'REQUIRED' - WHAT THE POINT?