refactor(api)!: rename toFumadocsSource() -> toDocsSource() (brand-neutral)

Renames the public doc-collection method across runtime, types, examples
and create-app templates so the API carries no upstream brand. The
internal helper and all call sites move together; fumadocs-core package
imports are untouched. Pairs with the .docs default outDir change.

BREAKING CHANGE: docs.toFumadocsSource() is now docs.toDocsSource().

Co-authored-by: Hanzo Dev <[email protected]>

examples/python/lib/source.ts

@@ -5,5 +5,5 @@ import { loader } from '@hanzo/docs-core/source';
 export const source = loader({
   // it assigns a URL to your pages
   baseUrl: '/docs',
-  source: docs.toFumadocsSource(),
+  source: docs.toDocsSource(),
 });