feat: add nix flake package and dev-shell

flake.nix

@@ -0,0 +1,88 @@
+{
+  description = "Media over QUIC - Gstreamer plugin";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+    crane.url = "github:ipetkov/crane";
+    rust-overlay = {
+      url = "github:oxalica/rust-overlay";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+  };
+
+  outputs = { self, nixpkgs, flake-utils, crane, rust-overlay}: 
+      flake-utils.lib.eachDefaultSystem (
+        system:
+        let
+          pkgs = import nixpkgs {
+            inherit system;
+            overlays = [ (import rust-overlay) ];
+          };
+          rust-toolchain = pkgs.rust-bin.stable.latest.default.override {
+            extensions = [
+              "rust-src"
+              "rust-analyzer"
+            ];
+          };
+         craneLib = (crane.mkLib pkgs).overrideToolchain rust-toolchain;
+
+          # Helper function to get crate info from Cargo.toml
+          crateInfo = cargoTomlPath: craneLib.crateNameFromCargoToml { cargoToml = cargoTomlPath; };
+
+          gstreamerLib = with pkgs ; [
+            gst_all_1.gstreamer.out
+            gst_all_1.gst-plugins-base
+            gst_all_1.gst-plugins-good
+            gst_all_1.gst-plugins-bad
+          ];
+          gstreamerSearch = with pkgs; [
+            gst_all_1.gst-plugins-ugly
+            gst_all_1.gst-plugins-rs
+          ] ++ gstreamerLib;
+
+          shell-deps = with pkgs; [
+            rust-toolchain
+            just
+            pkg-config
+            glib
+            cargo-sort
+            cargo-shear
+            cargo-edit
+            gst_all_1.gstreamer
+          ];
+
+          gstPluginPath = nixpkgs.lib.makeSearchPath "lib/gstreamer-1.0" gstreamerSearch + ":" + nixpkgs.lib.makeLibraryPath gstreamerLib;
+        in {
+          devShell = pkgs.mkShell {
+            packages = shell-deps;
+
+            env = {
+              GST_PLUGIN_PATH_1_0 = gstPluginPath;
+              #PKG_CONFIG_PATH = pkgConfigPath;
+              GST_REGISTRY = "./gst-registry.bin";
+            };
+
+            # if you want zsh instead of bash, uncomment this
+            #shellHook = ''
+            #  exec zsh
+            #'';
+          };
+          packages = {
+            hang-gst = craneLib.buildPackage (
+              crateInfo ./Cargo.toml
+              // {
+                src = craneLib.cleanCargoSource ./.;
+                nativeBuildInputs = with pkgs; [
+                  pkg-config
+                  glib
+                  glib.dev
+                  gst_all_1.gstreamer.dev
+                ];
+                cargoExtraArgs = "-p hang-gst";
+              }
+            );
+            default = self.packages.${system}.hang-gst;
+          };
+        });
+}