portable server with embedded for musl has different feature

packaging/musl/README.md

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+# Portable Linux server build
+
+This build produces one `x86_64` Linux server executable with embedded
+PostgreSQL. The Rust program is statically linked against musl. PostgreSQL is
+compiled against musl without optional host-library dependencies and is stored
+inside the executable by `postgresql_embedded`.
+
+PostgreSQL itself remains dynamically loadable so the `btree_gist` extension
+used by the migrations works. Its musl loader is included in the embedded
+archive, and static launcher executables invoke every PostgreSQL tool through
+that loader. Neither glibc, musl, PostgreSQL nor timezone data needs to be
+installed on the target machine.
+
+Build directly through the repository's Nix flake:
+
+```sh
+nix build '.?submodules=1#portable-server'
+```
+
+The `submodules=1` flag includes the workspace's nested Rust repositories. The
+artifact is available as `result/bin/server`. The derivation initializes a
+temporary cluster, creates `btree_gist`, sets the timezone to `UTC`, and checks
+that the final Rust executable has no ELF interpreter.
+
+The resulting executable is intended for 64-bit Linux kernels. Run it normally:
+
+```sh
+./result/bin/server server
+```
+
+Use the external PostgreSQL build on NixOS when preferred:
+
+```sh
+cargo build --release --package server --no-default-features
+```