feat(registry): add html-in-canvas tag to all VFX and caption blocks

All 12 blocks now share the 'html-in-canvas' tag, enabling:

  hyperframes add --tag html-in-canvas

This installs all VFX + caption blocks in one command.

registry/blocks/vfx-liquid-background/registry-item.json

@@ -10,7 +10,14 @@
     "height": 1080
   },
   "duration": 12,
-  "tags": ["vfx", "liquid", "webgl", "displacement", "background"],
+  "tags": [
+    "html-in-canvas",
+    "vfx",
+    "liquid",
+    "webgl",
+    "displacement",
+    "background"
+  ],
   "files": [
     {
       "path": "vfx-liquid-background.html",
@@ -18,4 +25,4 @@
       "type": "hyperframes:composition"
     }
   ]
-}
+}