ensure target priv/lib directory exists before copying precompiled .so

[ashneyderman]

Summary

When a dependent project does a fresh compile Zig.Command.compile!/1 fails with a File.CopyError ("no such file or directory") even though the source .so file is present — the missing piece is the destination directory.

This adds File.mkdir_p!(lib_dir) before the copy to ensure the target directory is created if it doesn't already exist.

Current behavior

➜  uname -a
Linux pop-os 6.17.9-76061709-generic #202511241048~1764607909~24.04~df6b2b6 SMP PREEMPT_DYNAMIC Mon D x86_64 x86_64 x86_64 GNU/Linux

➜  mix compile
Compiling 48 files (.ex)

11:21:17.412 [debug] skipping compile step for precompiled module
Elixir.ElixirOpentui.NIF, at
/tmp/Elixir.ElixirOpentui.NIF/Elixir.ElixirOpentui.NIF.x86_64-linux-gnu.so

11:21:17.413 [debug] destination library path: /home/alex/gh_ashneyderman/bun-temp/elix
ir-opentui/_build/dev/lib/elixir_opentui/priv/lib/Elixir.ElixirOpentui.NIF.so

11:21:17.413 [debug] transferring cached library from
/tmp/Elixir.ElixirOpentui.NIF/Elixir.ElixirOpentui.NIF.x86_64-linux-gnu.so to
/home/alex/gh_ashneyderman/bun-temp/elixir-opentui/_build/dev/lib/elixir_opentui/priv/l
ib/Elixir.ElixirOpentui.NIF.so

== Compilation error in file lib/elixir_opentui/nif.ex ==
** (File.CopyError) could not copy from
"/tmp/Elixir.ElixirOpentui.NIF/Elixir.ElixirOpentui.NIF.x86_64-linux-gnu.so" to
"/home/alex/gh_ashneyderman/bun-temp/elixir-opentui/_build/dev/lib/elixir_opentui/priv/
lib/Elixir.ElixirOpentui.NIF.so": no such file or directory
    (elixir 1.19.4) lib/file.ex:1080: File.cp!/3
    (zigler 0.16.0) lib/zig/command.ex:261: Zig.Command.compile!/1
    (zigler 0.16.0) lib/zig/compiler.ex:151: Zig.Compiler.compile/3
    (zigler 0.16.0) expanding macro: Zig.Compiler.__before_compile__/1
    lib/elixir_opentui/nif.ex:1: ElixirOpentui.NIF (module)
elixir-opentui git:(main) ✗
➜  ls -al /tmp/Elixir.ElixirOpentui.NIF/Elixir.ElixirOpentui.NIF.x86_64-linux-gnu.so
-rw-rw-r-- 1 alex alex 3912112 Jun  8 11:21
/tmp/Elixir.ElixirOpentui.NIF/Elixir.ElixirOpentui.NIF.x86_64-linux-gnu.so
elixir-opentui git:(main) ✗
➜  ll /home/alex/gh_ashneyderman/bun-temp/elixir-opentui/_build/dev/lib/elixir_opentui/
total 16
drwxrwxr-x  4 alex alex 4096 Jun  8 11:20 ./
drwxrwxr-x 17 alex alex 4096 Jun  8 11:19 ../
drwxrwxr-x  2 alex alex 4096 Jun  8 11:20 ebin/
drwxrwxr-x  2 alex alex 4096 Jun  8 11:18 .mix/

Changes

• lib/zig/command.ex: Added File.mkdir_p!(lib_dir) call before File.cp!/3 in the precompiled library transfer path.