Astro Starlight rollupOptions.input SSR build failure

Trap: rollupOptions.input should not be an html file when building for SSR (vite@7.3.6 config.js:33532) in an Astro Starlight site looks like an integration regression — it surfaces even with minimal injectScript("page", "// hello") and reproduces at HEAD with the original SVG reference and zero mermaid files in tree. Fix: first try rm -rf website/.astro website/node_modules/.astro && pnpm install — the .astro cache under both project root and node_modules is a known corruption site. If still failing, suspect vite 7.3.6 + Astro 7.1.x incompatibility under current pnpm/Volta env (downgrading astro 7.1.6→7.1.4 did NOT fix). Session: binpatch docs/any-binary-rebrand-v3, blocker unresolved at f75850b.