feat(editor): blog editor element with exact untouched value

- golem15-journal-blogeditor (BlogEditorElement): light-DOM element with a
  TipTap WYSIWYG tab and a Source tab that edits the exact HTML string
- The value is the exact served string until a user edit; external values
  go in with emitUpdate false; summer-change fires on user edits only and
  an echo set is a no-op
- StarterKit without the trailing node, links without target, rel or class;
  injectCSS false with the ProseMirror base rules in blogeditor.css under
  the element tag, colours from --c-* only
- Committed bundle embedded through admin.go; vitest smoke on an imported
  post fixture (footer, style block, spans, figure, table, entities)

plugin_test.go

@@ -98,6 +98,16 @@ func TestJournalSVGEmbed(t *testing.T) {
 		t.Fatalf("AdminFS missing journal-icon.svg: %v", err)
 	}
 	_ = f.Close()
+	bundle, err := fs.ReadFile(fsys, "assets/dist/blogeditor.js")
+	if err != nil {
+		t.Fatalf("AdminFS missing the Blog Editor bundle: %v", err)
+	}
+	if !strings.Contains(string(bundle), "golem15-journal-blogeditor") {
+		t.Fatal("blogeditor.js does not define golem15-journal-blogeditor")
+	}
+	if _, err := fs.Stat(fsys, "assets/dist/blogeditor.css"); err != nil {
+		t.Fatalf("AdminFS missing blogeditor.css: %v", err)
+	}
 	filter, err := fs.ReadFile(fsys, "controllers/posts/config_filter.yaml")
 	if err != nil {
 		t.Fatal(err)