Replace study lesson expanding cards with master-detail drill-down; v1.1.51

Studies section now uses a three-level navigation: study list → study detail
with compact sortable lesson rows → individual lesson editor. Eliminates the
40+ expanding AdminCollapsibleCard items for lessons, replacing them with a
compact table (drag handle, reference, title, live/draft status, edit/preview/
delete per row) and a focused lesson editor opened by clicking Edit. Prev/Next
navigation between lessons added. BsbFetchButton extracted as a standalone
component for the inline lesson editor.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

package.json

@@ -1,7 +1,7 @@
 {
   "name": "siteforge",
   "private": true,
-  "version": "1.1.50",
+  "version": "1.1.51",
   "type": "module",
   "scripts": {
     "dev": "vite",