feat: Notion-style block editor v1 + Move to Trash + fixes

- Block editor: 13 block types with contentEditable + vanilla JS event delegation
- Slash menu /: 14 commands, 100% vanilla JS (zero Alpine conflicts)
- Keyboard: Enter=new block, Shift+Enter=soft break, arrows navigate blocks
- Drag & drop: SortableJS with 6-dot handles on block-wrapper
- Move to Trash: DELETE /board/api/pages/{id} + instant sidebar cleanup
- Placeholders: 'New page' + 'Type / for commands' in gray (CSS :empty::before)
- Redirect after delete stays in project context via workspaceKey
- Fixes: title auto-save, cursor positioning, x-for keys, Sortable guard

app/db.py

@@ -152,6 +152,12 @@ def init_db():
             conn.execute("ALTER TABLE pages ADD COLUMN sort_order INTEGER NOT NULL DEFAULT 0")
         except sqlite3.OperationalError:
             pass
+        # Migration: add content_format for Notion-style block editor (v1.2.0+)
+        # 'markdown' = legacy textarea, 'blocks' = JSON array of block objects
+        try:
+            conn.execute("ALTER TABLE pages ADD COLUMN content_format TEXT NOT NULL DEFAULT 'markdown'")
+        except sqlite3.OperationalError:
+            pass
         conn.commit()