Add community shortcut to lesson sidebar; v1.2.7

Adds a "Discuss this lesson" link in the classroom sidebar that takes
the user directly to the community page pre-filtered to the current
lesson's sectionId, so they can jump into discussion without navigating
back to the study index first.

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

package.json

@@ -1,7 +1,7 @@
 {
   "name": "siteforge",
   "private": true,
-  "version": "1.2.6",
+  "version": "1.2.7",
   "type": "module",
   "scripts": {
     "dev": "vite",