chore: update all packages to latest versions

- aionui 2.1.4 -> 2.1.50
- desloppify 0.9.15 -> 1.0
- ds4 -> 2026-08-05 (b030961)
- freebuff 0.0.85 -> 0.0.142 (binary moved to GitHub releases)
- graphify 0.7.10 -> 0.9.35 (license Apache-2.0, fix sed patterns for versioned deps)
- hipengine 0.2.2 -> 0.3.0 (console script renamed to hipengine)
- kubernetes-mcp-server 0.0.62 -> 0.0.66 (requires go >= 1.26.3)
- mcp-gateway 2.11.0 -> 3.4.0 (requires rustc >= 1.95)
- omniroute 3.8.28 -> 3.8.49
- radar 1.6.1 -> 1.9.1 (drop obsolete lockfile sed patch)
- relay-free-llm -> 96e6c48, cerebras-cloud-sdk 1.67.0 -> 1.91.0
- stakpak 0.3.86 -> 0.3.88

Add nixpkgs-latest input for toolchains newer than the pinned nixpkgs.

flake.nix

@@ -3,6 +3,9 @@
 
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    # Newer nixpkgs whose toolchains are required by some packages:
+    # rustc >= 1.95 (mcp-gateway >= 3.4.0), go >= 1.26.3 (kubernetes-mcp-server >= 0.0.66).
+    nixpkgs-latest.url = "github:NixOS/nixpkgs/nixos-unstable";
     systems.url = "github:nix-systems/default";
     blueprint = {
       url = "github:numtide/blueprint";