v0.15.0

Live-DX overhaul: a server-driven live UI model. (sigil web live) provides live collections and streams over SSE with with-sigil-ui middleware and live-routes; ui.sgl adds page helpers (http-response/page), the sg-* form family, ui-response, ui-update (renamed from ui-morph, now morphs the element itself via outerHTML), and ui-routes with defaulted handler responses. flash-message is renamed to sg-flash-message.

Realigns dependencies to the current ecosystem: sigil ^0.17, sigil-http ^0.16.7 (requires the new sse-broadcast default handler), sigil-sxml ^0.15, sigil-nrepl ^0.16, plus a dev-dependencies block on sigil-test ^0.17. The client-side WASM render module is parked on a separate branch.