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/bun/template_data.go

@@ -220,8 +220,11 @@ func NewModelData(table *models.Table, schema string, typeMapper *TypeMapper, fl
 		Prefix:        GeneratePrefix(table.Name),
 	}
 
+	// Convert columns to fields (sorted by sequence or name)
+	columns := sortColumns(table.Columns)
+
 	// Find primary key
-	for _, col := range table.Columns {
+	for _, col := range columns {
 		if col.IsPrimaryKey {
 			// Sanitize column name to remove backticks
 			safeName := writers.SanitizeStructTagValue(col.Name)
@@ -240,8 +243,6 @@ func NewModelData(table *models.Table, schema string, typeMapper *TypeMapper, fl
 		}
 	}
 
-	// Convert columns to fields (sorted by sequence or name)
-	columns := sortColumns(table.Columns)
 	for _, col := range columns {
 		field := columnToField(col, table, typeMapper)
 		// Check for name collision with generated methods and rename if needed
@@ -335,6 +336,21 @@ func sortConstraints(constraints map[string]*models.Constraint) []*models.Constr
 	return result
 }
 
+// sortIndexes sorts indexes by sequence, then by name
+func sortIndexes(indexes map[string]*models.Index) []*models.Index {
+	result := make([]*models.Index, 0, len(indexes))
+	for _, idx := range indexes {
+		result = append(result, idx)
+	}
+	sort.Slice(result, func(i, j int) bool {
+		if result[i].Sequence > 0 && result[j].Sequence > 0 {
+			return result[i].Sequence < result[j].Sequence
+		}
+		return result[i].Name < result[j].Name
+	})
+	return result
+}
+
 // sortColumns sorts columns by sequence, then by name
 func sortColumns(columns map[string]*models.Column) []*models.Column {
 	result := make([]*models.Column, 0, len(columns))