Force Nix-owned OpenClaw config links

Home Manager should replace the generated openclaw.json target because Nix owns that file. Without force=true, Darwin deploys can fail when the existing config symlink points at the previous generation.

Tests: nix build --accept-flake-config .#checks.aarch64-darwin.ci --no-link

nix/modules/home-manager/openclaw/config.nix

@@ -205,6 +205,7 @@ let
         name = openclawLib.toRelative inst.configPath;
         value = {
           text = configJson;
+          force = true;
         };
       };
       configFile = configFile;