Update the shared test selector to accept hemx-axum's content-hashed runtime script path instead of the old fixed /hemx.js path.
req: axum/005
req: test/001
Generate a SHA-256 content hash for the embedded hemx runtime, expose the hashed path from hemx-axum, serve immutable runtime headers, and update examples to load the hemx-owned path instead of fixed /hemx.js URLs.
req: axum_integration/005