feat(pgsql): diff against the live database by default for direct output

Direct pgsql output (job output.conn_env, merge --output-conn) now reads the live
schema and executes only the differences. full_ddl: true (job option) or --full-ddl
(merge) restores the full idempotent DDL; file output is unchanged.

- compare PKs by columns, skip constraint-backed indexes, normalize index method,
  FK actions, serial/numeric types, default literals/casts and truncated names
- diff table and column comments instead of re-emitting them
- remove leftover ZZDUMP debug code

cmd/relspec/job.go

@@ -844,7 +844,7 @@ func writeJobOutput(rj *resolvedJob, db *models.Database, lg *jobLogger) error {
 		}
 		lg.logf("writing output to database env:%s", rj.outputConnEnv)
 		writerOpts := newWriterOptions("", o.Package, o.FlattenSchema, o.Types, o.ArrayNullable, o.ContinueOnError)
-		writerOpts.Metadata = map[string]interface{}{"connection_string": rj.outputConn}
+		writerOpts.Metadata = map[string]interface{}{"connection_string": rj.outputConn, "full_ddl": o.FullDDL}
 		return wpgsql.NewWriter(writerOpts).WriteDatabase(db)
 	}
 

cmd/relspec/merge.go

@@ -59,6 +59,7 @@ var (
 	mergeSkipTables    string // Comma-separated table names to skip
 	mergeVerbose       bool
 	mergeReportPath    string // Path to write merge report
+	mergeFullDDL       bool   // Execute full DDL instead of diffing the live pgsql database
 	mergeFlattenSchema bool
 )
 
@@ -127,6 +128,7 @@ func init() {
 	mergeCmd.Flags().BoolVar(&mergeSkipSequences, "skip-sequences", false, "Skip sequences during merge")
 	mergeCmd.Flags().StringVar(&mergeSkipTables, "skip-tables", "", "Comma-separated list of table names to skip during merge")
 	mergeCmd.Flags().BoolVar(&mergeVerbose, "verbose", false, "Show verbose output")
+	mergeCmd.Flags().BoolVar(&mergeFullDDL, "full-ddl", false, "pgsql database output: execute the full DDL instead of only the differences from the live database")
 	mergeCmd.Flags().StringVar(&mergeReportPath, "merge-report", "", "Path to write merge report (JSON format)")
 	mergeCmd.Flags().BoolVar(&mergeFlattenSchema, "flatten-schema", false, "Flatten schema.table names to schema_table (useful for databases like SQLite that do not support schemas)")
 }
@@ -443,6 +445,7 @@ func writeDatabaseForMerge(dbType, filePath, connString string, db *models.Datab
 		if connString != "" {
 			writerOpts.Metadata = map[string]interface{}{
 				"connection_string": connString,
+				"full_ddl":          mergeFullDDL,
 			}
 			// Add report path if merge report is enabled
 			if mergeReportPath != "" {