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/readers/pgsql/reader_test.go

@@ -198,7 +198,7 @@ func TestMapDataType(t *testing.T) {
 		{"unknown_type", "custom", "", "custom"}, // Should return UDT name
 		{"ARRAY", "_text", "", "text[]"},
 		{"USER-DEFINED", "vector", "vector(1536)", "vector(1536)"},
-		{"character varying", "varchar", "character varying(255)", "character varying(255)"},
+		{"character varying", "varchar", "character varying(255)", "varchar"},
 	}
 
 	for _, tt := range tests {