feat: relevance-ordered search, suggest rows and journal:reindex

- Engine search asks Typesense for the first 250 candidates, re-gates them
  in SQL, counts the gated rows and pages over them in rank order; pages
  after the first are no longer empty. An explicit sort overrides the rank.
- The settings row gates engine search, so it works straight after boot.
- ?fields=suggest serves id, title, slug, a plain-text excerpt,
  featured_image_url and published_at.
- Content is indexed as plain text; Post declares SearchIndexSchema.
- journal:reindex [--fresh] syncs every post into the index.

plugin.go

@@ -114,6 +114,7 @@ func (p *Plugin) Commands() []bonfire.Command {
 	return []bonfire.Command{
 		console.ExportPosts(p.app),
 		console.ImportPosts(p.app),
+		console.Reindex(p.app),
 	}
 }