docs(footer): record what v3.0.0 changes for this footer

No markup change: the element, the `privacy` slot, and emit-jsonld all carry
across 1.0.6 -> 3.0.0 untouched, and the bundle pin lives in document_head.hbs
one commit down. Two things the bump makes true are worth writing down where
the next reader will look.

LANGUAGE SWITCHER, deliberately off. v2.0.0 added a built-in English/日本語
control. It is opt-in, so this file already gets the right behaviour by saying
nothing — but "we never considered it" and "we considered it and said no" read
identically in a diff, and this is the second one. Its options resolve to the
locale's SITE ROOT on a foreign host, not to a translation of the current page
(footer-data.js: `path` is the fallback; _languageHref only does better on the
www family). So on a support page it would look like a page-language toggle and
actually be an exit to www.postman.com/jp/.

RESERVED HEIGHT, corrected. The comment claimed "no layout shift". Measured:
the component reserves 320px by default and mounts to ~647px desktop /
~1348px mobile, so it grows the page. This is not a regression — 1.0.6 was
worse (682/1517px against the same 320px) — and the footer is below the fold,
so the cost is scroll position rather than CLS on the first view. Left
unfixed here on purpose: a per-consumer override picks a number that goes stale
on the next parity change, and every consumer would pick their own. It belongs
in the component's default. Noted in the file with what to do if support needs
it solved sooner.

The destination diff in the previous commit still holds at 3.0.0 — 49 links,
same five columns, no additions or removals since 1.0.6. What did change is
labels, not targets: v2.0.0 split the visible label from the JSON-LD name, so
the footer now reads "App Security" / "About" / "Academy" where it read "App
Security APIs" / "About Postman" / "Postman Academy", matching what
www.postman.com renders. The SEO names survive in the emitted
SiteNavigationElement.

Verified in headless Chromium against the real 3.0.0 bundle: mounts with all
five columns and 50 links, the Do Not Sell button is assigned to the `privacy`
slot and visible, JSON-LD is emitted exactly once, the copyright computes 2026,
and no language switcher renders.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: ch264

templates/footer.hbs

@@ -4,17 +4,33 @@
   hand-inlined markup that duplicated the marketing site's footer.
 
   CLIENT-MOUNTED, unlike the navbar above. The footer is below the fold and not
-  LCP-critical, so there is no prerendered fragment; the element reserves its own
-  height (--pm-footer-min-height) and fills in on mount, so no layout shift.
-  It is registered by the same bundle the navbar's hydration uses — see
-  templates/document_head.hbs — so no extra script is needed here.
+  LCP-critical, so there is no prerendered fragment; the element reserves height
+  via --pm-footer-min-height and fills in on mount. It is registered by the same
+  bundle the navbar's hydration uses — see templates/document_head.hbs — so no
+  extra script is needed here.
+
+  That reserve is PARTIAL, not exact. The component's default is 320px, while the
+  mounted footer measures ~647px on desktop and ~1348px on mobile (v3.0.0, in
+  Chromium), so mount still grows the page. It is below the fold, so this costs
+  scroll position rather than CLS on the initial view. Not introduced here — the
+  same 320px default under-reserved at v1.0.6 too, by more (682/1517px). The fix
+  belongs in the component's default rather than in an override per consumer; if
+  it needs solving here first, set --pm-footer-min-height on this element behind
+  a media query rather than picking one value for both breakpoints.
 
   No `host` attribute: it falls back to location.origin, and support.postman.com
   is not www-family, so internal links resolve to absolute www.postman.com URLs.
 
   emit-jsonld is left ON (the default). Unlike the docs site, the support center
   has no competing SiteNavigationElement data of its own, so letting the
   component emit it is a net gain rather than a duplicate.
+
+  language-switcher is left OFF (also the default). v2.0.0 added a built-in
+  English/日本語 switcher, but its options point at www.postman.com/jp/, not at a
+  translation of the page you are on — a foreign host gets the site-root
+  fallback. On the support center that control would read as "switch this page's
+  language" and instead navigate the reader off the support center entirely.
+  Turn it on only alongside a decision about localized /hc/ URLs.
 --}}
 <div>
   <hr>