Adds a minimal SSR-only Leptos dashboard to the operator, gated by a new
`web-frontend` cargo feature. The whole frontend (HTML + Tailwind CSS) is
bundled into the binary via `include_str!`, no cargo-leptos / WASM / hydration
involved — air-gap clean, single container.
build.rs invokes the standalone tailwindcss v4 CLI when the feature is on.
Default builds are untouched.
Static skeleton only — no interactivity yet. Kept as a comparison baseline
for the Maud + HTMX variant on the next branch.
Jean-Gabriel Gill-Couture
5c769437dc