feat: sitemap settings singleton with content types and additional addresses

- one settings tile opening the golem15.sitemap.settings singleton
- Files tab (site address, file size, S1 files partial), Additional
  addresses repeater, Content types tab built from signpost at boot
- golem15_sitemap_types; a type switched off leaves the files (reason type)
- a save validates (errors.*) and dispatches a rebuild after commit

classes/dispatch.go

@@ -0,0 +1,66 @@
+package classes
+
+import (
+	"context"
+	"time"
+
+	"git.golem15.com/golem15/summercms/modules/backpack"
+	"git.golem15.com/golem15/summercms/modules/conga"
+	"git.golem15.com/golem15/summercms/modules/lagoon"
+	"git.golem15.com/golem15/summercms/modules/phrasebook"
+	"gorm.io/gorm"
+)
+
+// RebuildLabelKey is the phrase key of the rebuild job's label.
+const RebuildLabelKey = "golem15.sitemap::lang.jobs.rebuild"
+
+// buildingWindow bounds the "rebuilding now" state of the settings screen:
+// a request older than this without a finished rebuild (no worker runs)
+// is no longer shown as running.
+const buildingWindow = time.Hour
+
+// RequestRebuild records that a rebuild was asked for (the settings
+// screen's files.building state) and dispatches the rebuild job once db's
+// transaction commits, so the job reads what the transaction wrote. A
+// queue error is logged and never fails the caller.
+func RequestRebuild(ctx context.Context, app *backpack.App, db *gorm.DB) error {
+	if app == nil || db == nil {
+		return ErrNoDatabase
+	}
+	if err := db.Exec(`UPDATE golem15_sitemap_settings SET rebuild_requested_at = ? WHERE id = 1`, time.Now().UTC()).Error; err != nil {
+		return err
+	}
+	lagoon.AfterCommit(ctx, db, func(ctx context.Context, _ *gorm.DB) {
+		if _, err := DispatchRebuild(ctx, app); err != nil {
+			pluginLog.Warn("golem15.sitemap: queue rebuild", "error", err)
+		}
+	})
+	return nil
+}
+
+// DispatchRebuild dispatches the rebuild job now, with a summer_jobs row
+// labelled in the request locale, and returns the row id.
+func DispatchRebuild(ctx context.Context, app *backpack.App) (uint, error) {
+	db, ok := app.Lookup[*gorm.DB]()
+	if !ok || db == nil {
+		return 0, ErrNoDatabase
+	}
+	m, err := conga.From(app)
+	if err != nil {
+		return 0, err
+	}
+	label := RebuildLabelKey
+	if tr, ok := app.Lookup[*phrasebook.Translator](); ok && tr != nil {
+		label = tr.Get(ctx, RebuildLabelKey, nil)
+	}
+	return m.Dispatch(ctx, db.WithContext(ctx), RebuildArgs{}, conga.DispatchOpts{Label: label})
+}
+
+// Building reports whether a rebuild asked for from the admin has not
+// finished yet (within buildingWindow).
+func Building(requested, built *time.Time, now time.Time) bool {
+	if requested == nil || now.Sub(*requested) > buildingWindow {
+		return false
+	}
+	return built == nil || built.Before(*requested)
+}