`USER_PRESET_DIR` was exported with no production consumer — only the new test
read it, and a test that imports the implementation constant cannot catch that
constant being wrong. It stays module-internal, and the test spells the segment
it expects.
`Config.roots` defaulted to `[]`, so a deployment that did not patch both roots
in got a roster with none — `dsh run` once booted exactly that and failed
resolving `standard`. The user root never needed an app: `<dshHome>/.agent-presets`
is the same place in every deployment, resolvable here the way
`dsh-skill-local` resolves `<dshHome>/skills`.
The roster now derives that root itself unless `includeUserRoot` is false, and
`apps/cli` supplies only the SHIPPED root, whose path an installed app alone
can resolve. The derived root is appended after every configured root, so a
shipped id still shadows a home directory claiming it and `writableRoot()`
still prefers an explicitly configured `user` root; the set is resolved once at
construction, because a root set that changed between a `list()` and the
`copy()` acting on its answer would author into a directory the caller never
saw.
Every test that pins an exact roster now says `includeUserRoot: false` — the
machine's real harness home must not decide what a golden or an assertion
counts.
