Architecture for zero code duplication:
- Extract page editor HTML into _page_editor_content.html (shared include)
- page_editor.html includes it (same behavior as before)
- page_editor_embed.html includes it with empty topbar (no header in peek)
- board.py: ?embed=1 renders page_editor_embed.html
Peek panels now load /pages/{id}?embed=1 in iframe:
- Editor renders without sidebar or header breadcrumb/actions
- Full editing capability (blocks, markdown, slash commands, save)
- Same code — one change to _page_editor_content.html updates everywhere