nix flake reports v0.5.2 instead of latest v0.9.3

[nitrocode]

nix run github:stablyai/agent-slack -- --version reports 0.5.2, even
with --refresh to bypass the local flake cache. The latest published
release is v0.9.3 (also what npm i -g agent-slack / npx agent-slack@latest
installs).

Comparing main against the v0.9.3 tag:

gh api repos/stablyai/agent-slack/compare/main...v0.9.3 --jq '{status, ahead_by, behind_by}'
# {"status":"behind","ahead_by":0,"behind_by":42}

So main HEAD is 42 commits ahead of the v0.9.3 tag, yet the Nix build
reports a version even older than that tag. This suggests the flake's
version string (or its vendored build/lockfile) isn't being kept in sync
with package.json / npm releases.

Repro:

1. nix run github:stablyai/agent-slack --extra-experimental-features nix-command --extra-experimental-features flakes -- --version
   → 0.5.2
2. nix run github:stablyai/agent-slack --extra-experimental-features nix-command --extra-experimental-features flakes --refresh -- --version
   → still 0.5.2
3. npx -y agent-slack@latest --version → 0.9.3

Expected: the Nix flake build reflects the current main/release version,
or at minimum tracks the latest tagged release.

Environment: macOS, Nix 2.35.2 (flakes + nix-command experimental features).