fix: inject linux-musl sharp binaries into build/ to fix 502 on Dokploy

build.sh runs npm run build on macOS, so only the host's sharp binary
(darwin-arm64) got traced into the standalone output. The container
runs node:20-alpine (Linux, musl libc), which cannot load that binary
- the server crashed at runtime, causing a 502 even though the docker
build itself succeeded.

npm pack can fetch another platform's prebuilt sharp/libvips tarballs
without an install-time OS check, so build.sh now pulls the
linux-musl x64 and arm64 builds directly into build/node_modules and
drops the now-unused host binary.

build/.next/server/app/sitemap.xml/route.js

@@ -0,0 +1,7 @@
+var R=require("../../chunks/[turbopack]_runtime.js")("server/app/sitemap.xml/route.js")
+R.c("server/chunks/[externals]_next_dist_0arv.vj._.js")
+R.c("server/chunks/[root-of-the-server]__0j8-xkl._.js")
+R.c("server/chunks/node_modules_next_dist_1343e2k._.js")
+R.c("server/chunks/_next-internal_server_app_sitemap_xml_route_actions_036gxb_.js")
+R.m(83345)
+module.exports=R.m(83345).exports