nix(chore): set nixpkgs to nixos-26.05, update flake.lock (#495)

fixes #492
Co-authored-by: KristijanZic <kristijan.zic@10x.engineering>

flake.nix

@@ -1,7 +1,8 @@
 {
   description = "Nix Flake for lan-mouse";
   inputs = {
-    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    # 26.05 used here to keep allowing builds on x86_64-darwin, bump this to unstable once they deprecate 26.05
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-26.05";
     rust-overlay = {
       url = "github:oxalica/rust-overlay";
       inputs.nixpkgs.follows = "nixpkgs";
@@ -30,7 +31,24 @@
             let
               pkgs = import nixpkgs {
                 inherit system;
-                overlays = [ rust-overlay.overlays.default ];
+                overlays = [
+                  rust-overlay.overlays.default
+
+                  #NOTE: appstream's meson build injects the literal string
+                  # "none required" into linker flags on 'aarch64-darwin', causing clang to fail.
+                  # remove this overlay once we bump nixpkgs to unstable branch
+                  (
+                    final: prev:
+                    lib.optionalAttrs prev.stdenv.hostPlatform.isDarwin {
+                      appstream = prev.appstream.overrideAttrs (old: {
+                        postConfigure = (old.postConfigure or "") + ''
+                          substituteInPlace build.ninja \
+                            --replace-fail "none required" ""
+                        '';
+                      });
+                    }
+                  )
+                ];
               };
               # Default toolchain for devshell
               rustToolchain = pkgs.rust-bin.stable.latest.default.override {
@@ -80,7 +98,7 @@
                 libadwaita
                 librsvg
               ]
-              ++ lib.optionals pkgs.stdenv.isLinux [
+              ++ lib.optionals pkgs.stdenv.hostPlatform.isLinux [
                 libX11
                 libXtst
               ];