Draw the last native world labels through the label overlay

The Directions A and B letters and a data pack's media label were the two
Cesium text labels left, kept by an allow-list in noCesiumLabels.test.mjs.
Both now publish entries to the shared world-overlay host, and the
allow-list is gone, so any Cesium label in src is a test failure.

Directions publishes the letters to the directions-markers source; the
markers keep only their points. A clicked endpoint's letter hangs over the
surface that was clicked. One placed without a click stays hidden until its
ground-floor cell resolves, then requests a render, so a still camera shows
it; a cell that settles with no height falls back to the ellipsoid. Each
position is computed once.

A pack resource handle gains label(entry). The application passes its
shared overlay host to SceneDirector through dataPacks.overlayHost; without
one a media pack fails to load rather than drawing a native label. Each
labelled resource takes a source from a pool and returns it on dispose, as
the host never removes a source, so two presentations of one pack never
clear each other's labels and repeat loads add no sources. A label written
after dispose is ignored. The media label is protected, so it always draws
as before.

Live (Denver, keyless globe): a clicked A and a programmatic B both anchor
on their dots over 1.58 km ground. Documented in docs/CURRENT-STATE.md and
docs/DIRECTOR-DATA-PACKS.md.

docs/CURRENT-STATE.md

@@ -3463,8 +3463,14 @@ down | auth-failed` (plus the unchanged `missing-key`/`unsupported`) with
 >   celestial ring, annotations SVG, missions frame tick, and traffic).
 > - **World-label accounting:** All intended label/card migrations use the
 >   shared host. The former native `LabelGraphics` exception for cable reference
->   labels was retired on 2026-08-18; cable text may render over tile geometry,
->   so **zero native world-label creation sites remain**. The mission replay DOM vehicle, awareness
+>   labels was retired on 2026-08-18; cable text may render over tile geometry.
+>   The Directions A/B letters (`directions-markers` source) and data-pack media
+>   labels (a pooled `data-pack-labels:<n>` source per pack resource, through
+>   the pack handle's `label`) moved to the host on 2026-11-04, and
+>   `src/noCesiumLabels.test.mjs` no longer keeps an allow-list, so **zero
+>   native world-label creation sites remain**. A media pack shown without an
+>   `overlayHost` fails to load rather than drawing a native label. The mission
+>   replay DOM vehicle, awareness
 >   compass, annotation SVG callouts, and host-owned detection isolation target
 >   are explicit exceptions; the awareness ring and cockpit contact pips are
 >   non-text out-of-scope surfaces. Annotation callout text, geometry, leaders,