chore(auto): update flake inputs

[void-commander-brain-freeze]

CI repair report

Changes

• nix.nixPath → nix.settings.nix-path in profiles/defaults.nix. Nixpkgs
  renamed this NixOS option (nixos/modules/config/nix-channel.nix now
  defines settings.nix-path and aliases the old nix.nixPath to it via
  mkRenamedOptionModule). The replacement option has the exact same type
  (listOf str) and the exact same effect (it becomes NIX_PATH), so this
  is a pure rename with no behaviour change — moved the existing
  ["nixpkgs=${inputs.nixpkgs}"] value into the nix.settings block that
  already existed in the same file.

Needs a human

Nothing. The two other deprecation warnings in .ci-check.log are not
config options in this repo and were not introduced by this flake update
(neither nixpkgs input hash change nor any other bumped input touches
them):

• The package 'devenv-test'/'devenv-up' is deprecated. Use the corresponding devenv <cmd> commands. — this is a lib.warn baked into
  every package that inputs.devenv.flakeModule auto-generates from a
  devenv shell (see flake/devenv.nix). It nags at anyone who builds
  packages.<system>.devenv-test/devenv-up instead of running
  devenv test/devenv up. There is no option here to rename — the CI
  matrix already excludes devenv-up from flake/github-actions.nix and
  flake/buildkite-pipeline.nix, and this warning predates this update
  (the devenv input's lock entries are unchanged in this bump). Not
  touched.
• stdenv.isLinux is deprecated, use stdenv.hostPlatform.isLinux instead /
  same for isDarwin — does not originate from any .nix file in this
  repo (grepped, no matches); it comes from a third-party package's own
  build expression pulled in as a dependency during evaluation (visible
  right around the wezterm/niri/smithay fetches in the log). Fixing
  it would mean patching upstream code we don't own. Not touched.

nix run .#world -- check passes after the nix.nixPath fix, with only
the two pre-existing warnings above remaining, plus the intentional
rekey.hostPubkey warnings for the test/nixos placeholder hosts
(the warning text itself says this is expected until a real pubkey is
set).