chore: introduce nix configuration (#72)

Author: sunng87

.gitignore

@@ -1 +1,3 @@
 /target
+.direnv
+.envrc

flake.lock

@@ -0,0 +1,47 @@
+{
+  description = "Development environment flake";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.11";
+    fenix = {
+      url = "github:nix-community/fenix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, fenix, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+        pythonEnv = pkgs.python3.withPackages (ps: with ps; [
+          psycopg
+        ]);
+        buildInputs = with pkgs; [
+        ];
+      in
+      {
+        devShells.default = pkgs.mkShell {
+          nativeBuildInputs = with pkgs; [
+            pkg-config
+            git
+            mold
+            (fenix.packages.${system}.stable.withComponents [
+              "cargo"
+              "clippy"
+              "rust-src"
+              "rustc"
+              "rustfmt"
+              "rust-analyzer"
+            ])
+            cargo-nextest
+            curl
+            gnuplot ## for cargo bench
+            pythonEnv
+            postgresql
+          ];
+
+          LD_LIBRARY_PATH = pkgs.lib.makeLibraryPath buildInputs;
+        };
+      });
+}