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>

public/components/sv_card.js

@@ -1,14 +1,13 @@
 import { el } from '../dom.js';
 
 // Builds the refined-B chrome shell and returns { root, body }. The card module
-// fills `body` in its mount(); start()/stop() own its refresh timer.
+// fills `body` in its mount(); start()/stop() own its refresh timer. Position +
+// size are set by the Sacred Valley canvas (absolute geometry), not here.
+// Decorative cards (blank / blackflame) carry no title bar.
 export function svCard(def) {
   const body = el('div', { class: 'sv-card-body' });
-  const root = el('div', {
-      class: 'sv-card', dataset: { cardId: def.id },
-      style: { gridColumn: 'span ' + (def.span || 6) }   // 12-col grid; per-card width
-    },
-    el('div', { class: 'sv-card-title' }, def.title),
+  const root = el('div', { class: 'sv-card', dataset: { cardId: def.id } },
+    def.title ? el('div', { class: 'sv-card-title' }, def.title) : null,
     body
   );
   return { root, body };