fix(codegen): sort map iteration to make generated output deterministic

Table.Columns/Constraints/Indexes/Relationships are Go maps, and every
writer, reader, diff, inspector, and merge code path that iterated them
directly was subject to Go's randomized map order, so identical input
could produce different output (or a different in-report violation/diff
order) on every run. Most visibly this showed up as bun/gorm `unique:`
struct tags changing order across consecutive `make models` runs with no
source change.

Fixed by sorting map iteration (by Sequence then Name, or alphabetically
for string-keyed maps) everywhere the order affects generated output or
first-match tie-break logic, across the bun, gorm, sqlite, dbml, drawdb,
pgsql, prisma, graphql, typeorm, drizzle, and dctx writers; the dctx,
prisma, and typeorm readers; the shared models.GetPrimaryKey/
GetForeignKeys helpers; pkg/diff, pkg/inspector, and pkg/merge; and the
TUI column/relationship pickers in pkg/ui.

pkg/writers/pgsql/migration_writer.go

@@ -239,7 +239,8 @@ func (w *MigrationWriter) generateDropScripts(model *models.Schema, current *mod
 		}
 
 		// Check each constraint in current database
-		for constraintName, currentConstraint := range currentTable.Constraints {
+		for _, currentConstraint := range sortConstraints(currentTable.Constraints) {
+			constraintName := currentConstraint.Name
 			modelConstraint, existsInModel := modelTable.Constraints[constraintName]
 
 			shouldDrop := false
@@ -252,7 +253,8 @@ func (w *MigrationWriter) generateDropScripts(model *models.Schema, current *mod
 			if shouldDrop && currentConstraint.Type == models.PrimaryKeyConstraint {
 				// Drop FK constraints that depend on this PK before dropping the PK itself.
 				for _, otherTable := range current.Tables {
-					for fkName, fkConstraint := range otherTable.Constraints {
+					for _, fkConstraint := range sortConstraints(otherTable.Constraints) {
+						fkName := fkConstraint.Name
 						if fkConstraint.Type != models.ForeignKeyConstraint {
 							continue
 						}
@@ -310,7 +312,8 @@ func (w *MigrationWriter) generateDropScripts(model *models.Schema, current *mod
 		}
 
 		// Check indexes
-		for indexName, currentIndex := range currentTable.Indexes {
+		for _, currentIndex := range sortIndexes(currentTable.Indexes) {
+			indexName := currentIndex.Name
 			modelIndex, existsInModel := modelTable.Indexes[indexName]
 
 			shouldDrop := false
@@ -401,7 +404,7 @@ func (w *MigrationWriter) generateAlterTableScripts(schema *models.Schema, model
 	}
 
 	// Check each model column
-	for _, modelCol := range modelTable.Columns {
+	for _, modelCol := range sortColumns(modelTable.Columns) {
 		currentCol, exists := currentColumns[strings.ToLower(modelCol.Name)]
 
 		if !exists {
@@ -518,7 +521,8 @@ func (w *MigrationWriter) generateIndexScripts(model *models.Schema, current *mo
 
 		// Process primary keys first - check explicit constraints
 		foundExplicitPK := false
-		for constraintName, constraint := range modelTable.Constraints {
+		for _, constraint := range sortConstraints(modelTable.Constraints) {
+			constraintName := constraint.Name
 			if constraint.Type == models.PrimaryKeyConstraint {
 				foundExplicitPK = true
 				shouldCreate := true
@@ -603,7 +607,8 @@ func (w *MigrationWriter) generateIndexScripts(model *models.Schema, current *mo
 		}
 
 		// Process indexes
-		for indexName, modelIndex := range modelTable.Indexes {
+		for _, modelIndex := range sortIndexes(modelTable.Indexes) {
+			indexName := modelIndex.Name
 			// Skip primary key indexes
 			if strings.HasPrefix(strings.ToLower(indexName), "pk_") {
 				continue
@@ -697,7 +702,8 @@ func (w *MigrationWriter) generateForeignKeyScripts(model *models.Schema, curren
 		currentTable := currentTables[strings.ToLower(modelTable.Name)]
 
 		// Process each constraint
-		for constraintName, constraint := range modelTable.Constraints {
+		for _, constraint := range sortConstraints(modelTable.Constraints) {
+			constraintName := constraint.Name
 			if constraint.Type != models.ForeignKeyConstraint {
 				continue
 			}
@@ -787,7 +793,7 @@ func (w *MigrationWriter) generateCommentScripts(model *models.Schema, current *
 		}
 
 		// Column comments
-		for _, col := range modelTable.Columns {
+		for _, col := range sortColumns(modelTable.Columns) {
 			if col.Description != "" {
 				sql, err := w.executor.ExecuteCommentColumn(CommentColumnData{
 					SchemaName: model.Name,