feat(database): inline embed + Open button + side peek + title placeholder

- Page title placeholder: new pages created with empty title, CSS :empty::before shows 'New page' in gray
- Database is now inline embed within page (not full-page replacement)
- Embed block 'collection' renders database table via FlowDeckDB.renderInto()
- Open button in column 1 of each row opens page in side peek panel
- Side peek: iframe loading /pages/{id}?embed=1, close/fullscreen/resize
- DB scripts refactored as reusable DBInstance + global FlowDeckDB API

app/templates/page_editor.html

@@ -8,4 +8,5 @@ page_title %}{{ page.title }}{% endblock %} {% block topbar %}
 {% include "_page_editor_content.html" %}
 {% endblock %} {% block scripts %}
 {% include "_page_editor_scripts.html" %}
+{% include "_database_table_scripts.html" %}
 {% endblock %}