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/air-freight/page/server-reference-manifest.json

@@ -0,0 +1,17 @@
+{
+  "node": {
+    "40178d6214c1b2a677a6ba1e043a26ad439d28ae9a": {
+      "workers": {
+        "app/air-freight/page": {
+          "moduleId": 67113,
+          "async": false,
+          "exportedName": "sendEmailAction",
+          "filename": "src/actions/sendEmail.ts"
+        }
+      },
+      "exportedName": "sendEmailAction",
+      "filename": "src/actions/sendEmail.ts"
+    }
+  },
+  "edge": {}
+}