feat: H1 to H2 setting with the admin save conversion (tracer)

- content_h1_to_h2 and generic_anchors on the settings row (migration
  202610280001), Headings and links tab, config key
  golem15.journal.content_h1_to_h2 used when no settings row exists
- classes.ConvertH1 on the x/net/html tokenizer; the Blog Editor types
  convert while the setting is on and answer editor.h1_converted
- GET /posts/{slug} reports content_h1_to_h2 (additive key)

updates/202610280001_add_golem15_journal_settings_headings.go

@@ -0,0 +1,43 @@
+package updates
+
+import (
+	"github.com/go-gormigrate/gormigrate/v2"
+	"gorm.io/gorm"
+)
+
+// addSettingsHeadings adds the Headings and links settings to the
+// golem15_journal_settings row: content_h1_to_h2 (on by default, so a site
+// keeps converting H1 in Journal rich text to H2) and generic_anchors (the
+// link texts the editor warns about, one per line; NULL means the built-in
+// lists). Adding the columns rewrites no stored content.
+var addSettingsHeadings = []*gormigrate.Migration{
+	{
+		ID: "202610280001_add_golem15_journal_settings_headings",
+		Migrate: func(tx *gorm.DB) error {
+			for _, stmt := range []string{
+				`ALTER TABLE golem15_journal_settings ADD COLUMN content_h1_to_h2 BOOLEAN NOT NULL DEFAULT TRUE`,
+				`ALTER TABLE golem15_journal_settings ADD COLUMN generic_anchors TEXT NULL`,
+			} {
+				if err := tx.Exec(stmt).Error; err != nil {
+					return err
+				}
+			}
+			return nil
+		},
+		Rollback: func(tx *gorm.DB) error {
+			for _, stmt := range []string{
+				`ALTER TABLE golem15_journal_settings DROP COLUMN IF EXISTS generic_anchors`,
+				`ALTER TABLE golem15_journal_settings DROP COLUMN IF EXISTS content_h1_to_h2`,
+			} {
+				if err := tx.Exec(stmt).Error; err != nil {
+					return err
+				}
+			}
+			return nil
+		},
+	},
+}
+
+func init() {
+	Register(addSettingsHeadings...)
+}

updates/category_content_migration_test.go

@@ -28,9 +28,20 @@ func TestCategoryContentMigration(t *testing.T) {
 		t.Fatalf("migrate: %v", err)
 	}
 
-	all := All()
-	if last := all[len(all)-1].ID; last != "202610090001_add_content_to_golem15_journal_categories" {
-		t.Fatalf("last migration = %s, want 202610090001_add_content_to_golem15_journal_categories", last)
+	// The content column's step and the one before it: later migrations
+	// are rolled back with it, so the test does not depend on being last.
+	const contentStep = "202610090001_add_content_to_golem15_journal_categories"
+	previous := ""
+	for i, mig := range All() {
+		if mig.ID == contentStep {
+			if i == 0 {
+				t.Fatalf("%s is the first migration", contentStep)
+			}
+			previous = All()[i-1].ID
+		}
+	}
+	if previous == "" {
+		t.Fatalf("migration %s is not registered", contentStep)
 	}
 	if !gdb.Migrator().HasColumn("golem15_journal_categories", "content") {
 		t.Fatal("golem15_journal_categories.content missing")
@@ -49,8 +60,8 @@ func TestCategoryContentMigration(t *testing.T) {
 	if err := gdb.Exec(`UPDATE golem15_journal_categories SET content = '<p>x</p>' WHERE slug = 'uncategorized'`).Error; err != nil {
 		t.Fatal(err)
 	}
-	if err := m.RollbackLast(); err != nil {
-		t.Fatalf("rollback last: %v", err)
+	if err := m.RollbackTo(previous); err != nil {
+		t.Fatalf("rollback to %s: %v", previous, err)
 	}
 	if !gdb.Migrator().HasTable("golem15_journal_categories") {
 		t.Fatal("golem15_journal_categories dropped by the content rollback")

updates/settings_headings_migration_test.go

@@ -0,0 +1,72 @@
+package updates
+
+import (
+	"database/sql"
+	"fmt"
+	"testing"
+	"time"
+
+	"git.golem15.com/golem15/summercms/modules/lagoon"
+	"github.com/go-gormigrate/gormigrate/v2"
+)
+
+// TestSettingsHeadingsMigration checks the Headings and links columns:
+// content_h1_to_h2 defaults to true on the existing settings row,
+// generic_anchors is NULL, and the rollback drops both and keeps the row.
+func TestSettingsHeadingsMigration(t *testing.T) {
+	sqlDB := dedicatedDB(t, fmt.Sprintf("journal_settings_headings_%d", time.Now().UnixNano()))
+	gdb, err := lagoon.Use(t.Context(), sqlDB)
+	if err != nil {
+		t.Fatal(err)
+	}
+	backend := gormigrate.New(gdb, &gormigrate.Options{
+		TableName:      "summer_migrations_summercms_cabana",
+		UseTransaction: true,
+	}, lagoon.BackendAdminMigrations)
+	if err := backend.Migrate(); err != nil {
+		t.Fatalf("backend_users migrations: %v", err)
+	}
+	m := journalMigrator(gdb)
+	if err := m.Migrate(); err != nil {
+		t.Fatalf("migrate: %v", err)
+	}
+	assertUdt(t, gdb, "golem15_journal_settings", "content_h1_to_h2", "bool")
+	assertUdt(t, gdb, "golem15_journal_settings", "generic_anchors", "text")
+	var on bool
+	var anchors sql.NullString
+	if err := gdb.Raw(`SELECT content_h1_to_h2, generic_anchors FROM golem15_journal_settings WHERE id = 1`).Row().Scan(&on, &anchors); err != nil {
+		t.Fatal(err)
+	}
+	if !on || anchors.Valid {
+		t.Fatalf("settings row: content_h1_to_h2 = %v, generic_anchors = %v, want true and NULL", on, anchors)
+	}
+
+	const step = "202610280001_add_golem15_journal_settings_headings"
+	previous := ""
+	for i, mig := range All() {
+		if mig.ID == step && i > 0 {
+			previous = All()[i-1].ID
+		}
+	}
+	if previous == "" {
+		t.Fatalf("migration %s is not registered after another step", step)
+	}
+	if err := m.RollbackTo(previous); err != nil {
+		t.Fatalf("rollback to %s: %v", previous, err)
+	}
+	for _, column := range []string{"content_h1_to_h2", "generic_anchors"} {
+		if gdb.Migrator().HasColumn("golem15_journal_settings", column) {
+			t.Fatalf("%s survived rollback", column)
+		}
+	}
+	var rows int64
+	if err := gdb.Raw(`SELECT COUNT(*) FROM golem15_journal_settings WHERE id = 1`).Scan(&rows).Error; err != nil {
+		t.Fatal(err)
+	}
+	if rows != 1 {
+		t.Fatalf("settings rows after rollback = %d, want 1", rows)
+	}
+	if err := m.Migrate(); err != nil {
+		t.Fatalf("re-migrate: %v", err)
+	}
+}