fix(pgsql): strip backticks from column defaults in migration paths

Backtick-wrapped defaults (e.g. from GORM tags like `now()`) were only
stripped in the CREATE TABLE column-definition path, leaving raw
backticks in the ALTER COLUMN ... SET DEFAULT migration statement and
in the migration-generated CREATE TABLE template, producing invalid
SQL. Default-drift comparisons also compared raw values, so a
backtick-wrapped model default never matched the live DB default and
kept re-emitting redundant ALTER statements.

pkg/writers/pgsql/templates.go

@@ -530,7 +530,7 @@ func BuildCreateTableData(schemaName string, table *models.Table) CreateTableDat
 		}
 		if col.Default != nil {
 			if value, ok := col.Default.(string); ok {
-				colData.Default = writers.QuoteDefaultValue(value, col.Type)
+				colData.Default = writers.QuoteDefaultValue(stripBackticks(value), col.Type)
 			} else {
 				colData.Default = fmt.Sprintf("%v", col.Default)
 			}