The dashboard publish gate resolves `widget.dataset` against the boot-time stack, so a dataset saved through `PUT /meta/dataset` is a phantom `widget-dataset-unknown` until the runtime restarts

[hotlong]

Observed while running cloud's objectui pin-smoke (cloud#2008) against a local
run-stack.sh --with-ui --prod-like --seed runtime at framework e581457baaaf.

What happened

1. PUT /api/v1/meta/dataset/p2008_users?package=com.pin2008.smoke → 200
   {"success":true,"seq":2,"state":"active","message":"Saved dataset 'p2008_users' (env-wide, state=active)"}

2. GET /api/v1/meta/dataset/p2008_users → 200, the item comes back with
   _packageId: "com.pin2008.smoke" and _diagnostics: { valid: true }.
   GET /api/v1/meta/dataset lists it alongside the five code-package datasets.

3. PUT /api/v1/meta/dashboard/p2008_dash?package=com.pin2008.smoke with three widgets, each
   dataset: "p2008_users" → 422, three widget-dataset-unknown issues:

   dataset "p2008_users" does not resolve to a declared dataset.
   hint: Declared datasets: sys_user_metrics, sys_organization_metrics, sys_session_metrics,
   sys_package_installation_metrics, sys_audit_log_metrics

   The hint enumerates ONLY the code-package datasets — the just-saved, readable,
   valid: true runtime one is missing from the gate's resolution universe.

4. POST /api/v1/meta/dataset/p2008_users/publish → 200. Retry step 3 → same 422.

5. Restarted the runtime process (nothing else changed — same workdir, same tenant DB).
   Replayed step 3 byte for byte → 200, dashboard saved, and it renders correctly.

So the dashboard author-time gate resolves widget.dataset against a universe built at kernel
boot, while GET /meta/dataset reads through to the store. A dataset and a dashboard authored
in the same session cannot be saved in that order without a restart, and the 422 names the
author's own dataset as nonexistent while the read API returns it.

Why this reads as a defect rather than a config

runtime-gate.ts documents datasets as "the live dataset declarations (stack key datasets)
… the resolution universe validateWidgetBindings links a widget's dataset / dimensions /
values against", added by objectui#7529 precisely so a per-write dashboard snapshot does not
report phantom widget-dataset-unknown on a board bound to a real dataset. The phantom shape
that docblock describes is exactly what a runtime-stored dataset still produces — the
collection appears to be populated from the boot-time stack rather than from the live metadata
store, so the fix that landed for declared datasets does not reach authored ones.

This is the door AI authoring goes through: an agent that creates a dataset and then a
dashboard in one turn gets a hard 422 blaming its own artifact, with a hint that lists
everything except the thing it just made.

Repro

Any runtime with --prod-like; a writable package; the two PUTs above in that order.

Filed from cloud#2008 (objectui pin bump). Not fixed there — cloud only pins objectui.