feat(nix): add development environment flake

- Add Nix flake for reproducible development environment
- Auto-detect Node.js and pnpm versions from package.json
- Configure development tools (gcc, python3, vips, etc.)
- Add shell hook with helpful development commands

Author: lessuselesss

flake.nix

@@ -0,0 +1,156 @@
+{
+  description = "Eliza development environment";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = {
+    self,
+    nixpkgs,
+    flake-utils,
+  }:
+    flake-utils.lib.eachDefaultSystem (system: let
+      pkgs = import nixpkgs {inherit system;};
+
+      # Read versions from package.json
+      packageJson = builtins.fromJSON (builtins.readFile ./package.json);
+      versions = let
+        # Extract version from packageManager string (e.g., "pnpm@9.12.3+sha512...")
+        pnpmFull = packageJson.packageManager or "pnpm@9.12.3";
+        pnpmVersion = builtins.head (builtins.match "pnpm@([^+]+).*" pnpmFull);
+      in {
+        nodejs = builtins.replaceStrings ["^" "~"] ["" ""] packageJson.engines.node;
+        pnpm = pnpmVersion;
+      };
+
+      # Function to fetch Node.js tarball with hash
+      fetchNodeJs = version: platform: arch:
+        pkgs.fetchurl {
+          url = "https://nodejs.org/dist/v${version}/node-v${version}-${platform}-${arch}.tar.gz";
+          hash = null; # Nix will provide the correct hash when it fails
+        };
+
+      # Function to fetch pnpm tarball with hash
+      fetchPnpm = version:
+        pkgs.fetchurl {
+          url = "https://registry.npmjs.org/pnpm/-/pnpm-${version}.tgz";
+          hash = null; # Nix will provide the correct hash when it fails
+        };
+
+      # Define specific Node.js version
+      nodejs = pkgs.stdenv.mkDerivation rec {
+        pname = "nodejs";
+        version = versions.nodejs;
+
+        src =
+          fetchNodeJs version
+          (
+            if pkgs.stdenv.isDarwin
+            then "darwin"
+            else "linux"
+          )
+          (
+            if pkgs.stdenv.isx86_64
+            then "x64"
+            else "arm64"
+          );
+
+        installPhase = ''
+          mkdir -p $out
+          cp -r ./* $out/
+          chmod +x $out/bin/node
+          chmod +x $out/bin/npm
+          chmod +x $out/bin/npx
+        '';
+
+        dontStrip = true;
+      };
+
+      # Define specific pnpm version
+      pnpm = pkgs.stdenv.mkDerivation {
+        name = "pnpm";
+        version = versions.pnpm;
+
+        src = fetchPnpm versions.pnpm;
+
+        buildInputs = [nodejs];
+
+        installPhase = ''
+          # Create directories
+          mkdir -p $out/{lib,bin}
+
+          # Extract tarball
+          cd $out/lib
+          tar xzf $src --strip-components=1
+
+          # Create the executable
+          cat > $out/bin/pnpm << EOF
+          #!${nodejs}/bin/node
+          require(process.env.PNPM_DIST || require('path').resolve(__dirname, '../lib/dist/pnpm.cjs'))
+          EOF
+
+          chmod +x $out/bin/pnpm
+
+          # Export the dist path
+          mkdir -p $out/nix-support
+          echo "export PNPM_DIST=\"$out/lib/dist/pnpm.cjs\"" >> $out/nix-support/setup-hook
+        '';
+
+        dontStrip = true;
+      };
+
+      # Define development tools separately
+      devTools = with pkgs; [
+        nixpkgs-fmt
+        remarshal
+        gcc
+        gnumake
+        python3
+        vips
+        libopus
+        rabbitmq-server
+        pkg-config
+        pnpm # Our specific pnpm version
+      ];
+    in {
+      devShells.default = pkgs.mkShell {
+        buildInputs = devTools;
+
+        shellHook = ''
+          echo "Welcome to Eliza development environment"
+
+          # Ensure project-specific Node.js takes precedence
+          export PATH="${nodejs}/bin:$PATH"
+
+          # Set up pnpm environment
+          export PNPM_HOME="$HOME/.local/share/pnpm"
+          export PATH="$PNPM_HOME:$PATH"
+
+          # Ensure PNPM_HOME exists
+          mkdir -p "$PNPM_HOME"
+
+          # Set up development environment variables
+          export NODE_ENV="development"
+          export VERBOSE="true"
+          export DEBUG="eliza:*"
+
+          # Print available commands
+          echo "Available commands:"
+          echo "  pnpm i  - Install dependencies"
+          echo "  pnpm build    - Build the project"
+          echo "  pnpm dev      - Start development server"
+          echo "  pnpm test     - Run tests"
+
+          # Print actual environment versions
+          node_version=$(${nodejs}/bin/node --version)
+          pnpm_version=$(pnpm --version)
+          echo "Node.js version: $node_version"
+          echo "pnpm version: $pnpm_version"
+        '';
+      };
+
+      formatter = pkgs.nixpkgs-fmt;
+    });
+}