feat(registry): rename caption-texture-lava to caption-texture with multi-texture support

Rename component to caption-texture and bundle 6 popular textures
(lava, marble, metal, wood, concrete, rock). The texture is configurable
via the texture composition variable (default: lava).

Usage: hyperframes render --variables '{"texture":"marble-012"}'

Tested: lava, marble-012, metal-046-b all render correctly with
distinct visual patterns.

registry/registry.json

@@ -128,7 +128,7 @@
       "type": "hyperframes:component"
     },
     {
-      "name": "caption-texture-lava",
+      "name": "caption-texture",
       "type": "hyperframes:component"
     },
     {