Cover: empty dirs, deeply nested paths, sub/../.. traversal, sibling
prefix attack, dotfiles, symlink exclusion, ENOENT/ENOTDIR errors,
FIFO filtering, logger invocation, and no-logger path.

Two new tests verify behavior after refresh: consecutive refreshes
fully replace the tree (no ghost entries from previous loads), and
directory-before-file sorting holds after refresh.

Extract reusable assertion helpers (assertTreeRenders, assertDirsBeforeFiles,
assertExpandShowsChildren) and add an "after refresh" describe block that
mounts → refreshes → re-runs the same checks. Catches bugs where refresh
leaves Ark UI TreeView or the collection signal in a broken state that only
surfaces on subsequent interactions.

Also adds: expand test, error-then-refresh recovery test.

Bug: after expanding a directory then refreshing, the expanded directory
could not be re-expanded — Ark UI's internal load tracking persisted
across collection replacements, thinking children were already loaded.

Fix: bump a treeKey counter on every loadRoot, use it to key the
TreeView.Root via <For each={[treeKey()]}> so SolidJS destroys and
recreates the component, clearing all internal Ark UI state.

Found by the new "expand → refresh → expand" component test.

…type

Eliminates parallel type definitions for the same domain concept.
listDir now returns FsDirEntry[] directly from the Zod schema.

# Conflicts:
#	default.nix

Master PR #507 introduced platform-specific pnpmDeps hashes. This
branch added @ark-ui/solid and @solidjs/testing-library, which
invalidate master's Darwin hash. Linux hash verified locally; Darwin
hash must be captured from CI output.

Captured from CI: the new pure-JS deps (@ark-ui/solid,
@solidjs/testing-library) produce the same pnpm store hash on both
Darwin and Linux, so both branches get the same sha256.

Previous commit wrongly set darwin hash equal to linux. Per #509,
these MUST differ because pnpm-lock.yaml contains platform-gated
optionalDependencies.

Verified empirically: on this branch, the darwin fetchPnpmDeps produces
the same content hash as linux. Build log at a82646d shows:
  - ran genuinely on darwin (/private/var/folders/ paths)
  - fetchPnpmDeps uses 'pnpm --force' which downloads ALL platform
    variants regardless of stdenv (sharp-libvips-{linux,darwin,linuxmusl}-*
    all fetched)
  - got: sha256-xcT+qRNmGjF7FmvPv4X25RlntZN8SAiVdWqH4lreS5o=

The #509 comment ('hashes differ by platform') was accurate for master,
but this branch's deps changes collapsed the distinction. The if-split
is kept to preserve master's architecture.

After the nix build, run the derivation's binary to catch
cross-platform cache hits. fetchPnpmDeps content hashes can match
across platforms, letting Nix serve the wrong-platform build from
cache — 'nix build' alone won't notice, but invoking the binary will
fail immediately on the wrong OS/arch.

Added to both _linux-fanout (parallel with home-manager, e2e) and
_darwin (serial before e2e — smoke is faster, so fail fast).

Restore default.nix and ci/mod.just to match origin/master. Master
already has the equivalent binary-smoke CI step (renamed 'run') which
supersedes this branch's 'smoke' iteration.