Expose generated ui::page as the canonical page-boundary rendering helper and move the Workout golden path and docs off beginner-visible ui::render calls.
req: public_api/002
req: codegen/002
req: canonical_authoring/006
Replace fixed /hemx.js wording with helper-provided runtime asset language so docs match hemx-axum runtime_js_path deployment boundaries.
req: axum_integration/005
req: examples/001