feat(docs): add MDX sandbox previews

docs/src/components/sandbox/registry.ts

@@ -0,0 +1,24 @@
+import type { SandboxDefinition } from "./types"
+
+type SandboxManifestModule = {
+  default: SandboxDefinition
+}
+
+const manifestModules = import.meta.glob<SandboxManifestModule>(
+  "../../sandboxes/*/*/sandbox.ts",
+  { eager: true }
+)
+
+const sandboxDefinitions = new Map<string, SandboxDefinition>()
+
+for (const module of Object.values(manifestModules)) {
+  const definition = module.default
+  if (sandboxDefinitions.has(definition.id)) {
+    throw new Error(`Duplicate sandbox id: ${definition.id}`)
+  }
+  sandboxDefinitions.set(definition.id, definition)
+}
+
+export function getSandboxDefinition(id: string) {
+  return sandboxDefinitions.get(id)
+}