Split runtime node_modules into reusable layers

- Add shared installFlags support to the common Bun node_modules builder
- Factor base and desktop overlay node_modules derivations for reuse
- Reuse the new runtime node_modules outputs in desktop and server builds

packages/node-modules-layers.nix

@@ -0,0 +1,58 @@
+{
+  lib,
+  pkgs,
+  src,
+}: let
+  common = pkgs.callPackage ./common.nix {};
+
+  t3codeNodeModulesBase = common.mkNodeModules {
+    pname = "t3code";
+    version = "base";
+    inherit src;
+    outputHash = "sha256-eXNOHRuNv9XFhXmsFtkunZswtRPd8gzJB1Jdw2DxYZY=";
+    filters = [
+      "."
+      "./apps/server"
+      "./apps/web"
+      "./packages/client-runtime"
+      "./packages/contracts"
+      "./packages/effect-acp"
+      "./packages/effect-codex-app-server"
+      "./packages/shared"
+    ];
+  };
+
+  t3codeNodeModulesDesktopOverlay = common.mkNodeModules {
+    pname = "t3code-desktop-overlay";
+    version = "overlay";
+    inherit src;
+    outputHash = "sha256-P6hlfpIZOLmkdXn99e0WC1CHAf7SD4CjouVwvAYo0+w=";
+    filters = [
+      "."
+      "./apps/desktop"
+    ];
+    impureEnvVars =
+      lib.fetchers.proxyImpureEnvVars
+      ++ [
+        "GIT_PROXY_COMMAND"
+        "SOCKS_SERVER"
+      ];
+    extraNativeBuildInputs = [
+      pkgs.gcc
+      pkgs.gnumake
+      pkgs.pkg-config
+      pkgs.python3
+    ];
+    extraEnv = ''
+      export ELECTRON_SKIP_BINARY_DOWNLOAD=1
+      export PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD=1
+      export npm_config_build_from_source=true
+    '';
+  };
+
+in {
+  inherit
+    t3codeNodeModulesBase
+    t3codeNodeModulesDesktopOverlay
+    ;
+}