feat(sacred-valley): hybrid free/snap canvas + blank & blackflame cards (2.8.0)

Replace masonry grid with an absolute-positioned 12-col canvas: drag to
move, corner to resize, per-card free/overlap toggle (Alt = no-snap).
Geometry persisted (migration 027: dashboard_layout.geom + extras).
Two new addable decorative cards: blank spacer + animated blackflame
(canvas particle flame). Old layout auto-migrates by flow-placement.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "void-server",
-  "version": "2.7.0",
+  "version": "2.8.0",
   "type": "module",
   "private": true,
   "scripts": {