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/node_modules/@img/sharp-libvips-linuxmusl-x64/versions.json

@@ -0,0 +1,30 @@
+{
+  "aom": "3.13.1",
+  "archive": "3.8.2",
+  "cairo": "1.18.4",
+  "cgif": "0.5.0",
+  "exif": "0.6.25",
+  "expat": "2.7.3",
+  "ffi": "3.5.2",
+  "fontconfig": "2.17.1",
+  "freetype": "2.14.1",
+  "fribidi": "1.0.16",
+  "glib": "2.86.1",
+  "harfbuzz": "12.1.0",
+  "heif": "1.20.2",
+  "highway": "1.3.0",
+  "imagequant": "2.4.1",
+  "lcms": "2.17",
+  "mozjpeg": "0826579",
+  "pango": "1.57.0",
+  "pixman": "0.46.4",
+  "png": "1.6.50",
+  "proxy-libintl": "0.5",
+  "rsvg": "2.61.2",
+  "spng": "0.7.4",
+  "tiff": "4.7.1",
+  "vips": "8.17.3",
+  "webp": "1.6.0",
+  "xml2": "2.15.1",
+  "zlib-ng": "2.2.5"
+}