feat(ipa): Register IPA components in global MDX scope

ipa/dev/component-fixtures.mdx

@@ -9,13 +9,6 @@ description:
   production builds."
 ---
 
-import {
-  Guidelines,
-  Guideline,
-  Example,
-  Workflow,
-} from "@site/src/components/ipa";
-
 # Component fixtures
 
 This page is not shipped — `draft: true` excludes it from production. Each

src/theme/MDXComponents/index.tsx

@@ -0,0 +1,20 @@
+import MDXComponents from "@theme-original/MDXComponents";
+import {
+  Guidelines,
+  Guideline,
+  Example,
+  Workflow,
+} from "@site/src/components/ipa";
+
+// Register the IPA authoring components in Docusaurus' global MDX scope so
+// guideline documents can use <Guidelines>, <Guideline>, <Example.*>, and
+// <Workflow> without an import in every file. PrincipleHeader is intentionally
+// omitted — it is auto-injected from frontmatter by the DocItem/Content
+// swizzle, not authored inline.
+export default {
+  ...MDXComponents,
+  Guidelines,
+  Guideline,
+  Example,
+  Workflow,
+};