feat(merge): enhance type conflict detection for columns

* Introduced extractTypeParts function to handle embedded dimensions in type strings.
* Updated columnTypeConflict to utilize new type extraction logic.
* Improved PostgreSQL type normalization and handling in various components.

pkg/pgsql/datatypes.go

@@ -45,6 +45,7 @@ var GoToStdTypes = map[string]string{
 	"sqldate":         "date",
 	"sqltime":         "time",
 	"sqltimestamp":    "timestamp",
+	"time.Time":       "timestamp",
 }
 
 var GoToPGSQLTypes = map[string]string{
@@ -90,6 +91,7 @@ var GoToPGSQLTypes = map[string]string{
 	"sqldate":         "date",
 	"sqltime":         "time",
 	"sqltimestamp":    "timestamp",
+	"time.Time":       "timestamp",
 	"citext":          "citext",
 }
 
@@ -135,6 +137,62 @@ func ConvertSQLType(anytype string) string {
 	return anytype
 }
 
+// PGTypeCanonical maps PostgreSQL type aliases and synonyms to their canonical base name.
+// Input should be a base type (no dimension parameters, lowercase).
+var PGTypeCanonical = map[string]string{
+	// integer aliases
+	"int":  "integer",
+	"int4": "integer",
+	"int2": "smallint",
+	"int8": "bigint",
+	// float aliases
+	"float4": "real",
+	"float8": "double precision",
+	// bool alias
+	"bool": "boolean",
+	// char aliases
+	"character":         "char",
+	"character varying": "varchar",
+	"bpchar":            "char",
+	// timestamp aliases
+	"timestamp without time zone": "timestamp",
+	"timestamp with time zone":    "timestamptz",
+	// time aliases
+	"time without time zone": "time",
+	"time with time zone":    "timetz",
+	// decimal alias
+	"decimal": "numeric",
+}
+
+// knownPGBaseTypes is the set of canonical PostgreSQL base types (no aliases).
+var knownPGBaseTypes = map[string]struct{}{
+	"integer": {}, "bigint": {}, "smallint": {},
+	"serial": {}, "bigserial": {}, "smallserial": {},
+	"numeric": {}, "real": {}, "double precision": {}, "money": {},
+	"varchar": {}, "char": {}, "text": {}, "citext": {},
+	"boolean": {},
+	"date": {}, "time": {}, "timetz": {}, "timestamp": {}, "timestamptz": {}, "interval": {},
+	"uuid": {}, "json": {}, "jsonb": {}, "bytea": {},
+	"inet": {}, "cidr": {}, "macaddr": {}, "xml": {},
+}
+
+// NormalizePGType maps a PostgreSQL base type (no dimension parameters) to its
+// canonical form. Unknown types are returned as-is (lowercased).
+func NormalizePGType(baseType string) string {
+	lower := strings.ToLower(strings.TrimSpace(baseType))
+	if canonical, ok := PGTypeCanonical[lower]; ok {
+		return canonical
+	}
+	return lower
+}
+
+// IsKnownPGBaseType reports whether the given name (after NormalizePGType) is a
+// recognized built-in PostgreSQL type. Custom types (e.g. vector, postgis) return false.
+func IsKnownPGBaseType(baseType string) bool {
+	_, ok := knownPGBaseTypes[strings.ToLower(strings.TrimSpace(baseType))]
+	return ok
+}
+
 func IsGoType(pTypeName string) bool {
 	for k := range GoToStdTypes {
 		if strings.EqualFold(pTypeName, k) {