[pull] master from cube-js:master - #660

…11533)

* docs: document time zones — account policy, personal, dashboard, and embed

CUB-852 shipped a tenant-wide time-zone policy with a personal override and embed
overrides, and CUB-3751 then gave a dashboard and a saved exploration a zone of
their own. None of it had a doc home.

Two new pages, because the topic genuinely had none — settings on the Admin →
Settings page are documented on their feature page, and there is no such page for
time zones:

- `admin/time-zones` — the authoritative one: what a zone actually changes
  (bucketing, relative dates, filter boundaries), the three admin controls, the
  personal zone, a dashboard's three choices and when a reader may borrow another
  zone, the exploration zone, the full resolution order, and why bare UTC offsets
  are rejected.
- `embedding/iframe/time-zones` — mirrors the existing localization page, whose
  shape this feature repeats exactly: account default, `?timezone=`, and a
  runtime `cube:action:set-timezone`.

Plus four surgical edits: a Time zone row and section on the Preferences page,
`cube:action:set-timezone` in the events reference, a note that
CUBEJS_DEFAULT_TIMEZONE is now the fallback rather than the only answer, and a
cross-link from the Core Data APIs time-zone section.

Written against the shipped code rather than the tickets, which corrected one
thing: the embed zone is account-wide at Admin → Embed → Settings, not
per-embed-tenant as CUB-3754 describes.

* docs: use the existing time-zone terms, and say what a viewer-resolved embed does

Review feedback on #11533, all five threads.

The invented term went out. "Account Time Zone" is what the console UI calls it, but
these docs already document that setting as **Default time zone** backed by
CUBEJS_DEFAULT_TIMEZONE — so a second capitalized name meant a reader searching for
it landed only on the three new pages. Worse, the docs taxonomy puts Account ABOVE
Deployment, so "the deployment's Account Time Zone" read as a contradiction on a page
that also documents a genuinely account-scoped zone. All 11 uses across the three
pages now say "the deployment's default time zone", first use per page linked to the
existing section.

"Tenant" is likewise not a docs term (it appears elsewhere only inside example
hostnames). It survives in exactly one place — the verbatim UI label in the controls
table — with a line under the table reconciling the label with the scope name the
docs use. Prose everywhere else says account-wide zone.

The embed page gained the two things it was missing: a plan-availability Note, and an
answer to "what does Viewer time zone mean when the viewer has no Cube account?" In
signed embedding it has none, so a viewer-resolved dashboard falls through to the
account default — supply ?timezone= if you want each end user's own zone. That
follows from the resolver: the personal zone is only consulted for mode 'viewer', and
an absent one falls through to what the artifact inherits.

Also moved the Preferences Time zone section below Language so section order matches
the table above it.

On the plan Note: I added it to the EMBED page only. Both sibling pages that carry
one agree on a Premium floor, and iframe embedding is the gated surface, so
"Premium and above plans" (the phrasing CLAUDE.md prescribes) is safe there. The
admin page still has none — I found no plan or feature-flag gate for the policy
itself, and guessing a tier is worse than omitting it. Note the group is not
uniform: 4 of the 7 iframe pages carry no plan note at all.