nix: rename custom -> packages

nix/packages/fish-lsp/default.nix

@@ -0,0 +1,51 @@
+{
+  mkYarnPackage,
+  fetchFromGitHub,
+  fetchYarnDeps,
+  fish,
+  fixup-yarn-lock,
+  nodejs,
+  yarn,
+  makeWrapper,
+}:
+
+mkYarnPackage rec {
+  pname = "fish-lsp";
+  version = "1.0.7";
+
+  src = fetchFromGitHub {
+    owner = "ndonfris";
+    repo = pname;
+    rev = "v${version}";
+    sha256 = "sha256-Np7ELQxHqSnkzVkASYSyO9cTiO1yrakDuK88kkACNAI=";
+  };
+
+  offlineCache = fetchYarnDeps {
+    yarnLock = src + "/yarn.lock";
+    hash = "sha256-hmaLWO1Sj+2VujrGD2A+COfVE2D+tCnxyojjq1512K4=";
+  };
+
+  nativeBuildInputs = [
+    fish
+    fixup-yarn-lock
+    nodejs
+    yarn
+    makeWrapper
+  ];
+
+  buildPhase = ''
+    runHook preBuild
+    wasm_file=$(find node_modules -type f -a -name tree-sitter-fish.wasm)
+    cp -f $wasm_file ./deps/fish-lsp
+    yarn run sh:build-time
+    yarn --offline compile
+    yarn run sh:relink
+    # yarn run sh:build-completions
+    runHook postBuild
+  '';
+
+  postInstall = ''
+    wrapProgram "$out/bin/fish-lsp" \
+        --set-default fish_lsp_logfile "/tmp/fish_lsp_logs.txt"
+  '';
+}