feat(build): make generated page helper canonical

Move canonical examples and docs snippets from raw render/page calls to generated ui::page helpers, hide generated render behind doc(hidden), and let form resources participate in generated target inspection for tests.

req: canonical_authoring/005

req: dx/006

req: codegen/002

req: public_api/002

req: test/001

examples/kanban/src/lib.rs

@@ -37,7 +37,7 @@ mod tests {
     // req: html_safety/002 req: view/001 req: test/005
     #[test]
     fn kanban_board_test_payload_is_rendered_by_a_hemplate_view() {
-        let html = super::ui::render(&empty_board());
+        let html = super::ui::page(&empty_board());
         let document = Html::parse_fragment(html.as_str());
         assert_eq!(document.select(&selector(".columns")).count(), 1);
     }