Keep the ridden aircraft's layer when Contacts ends, and clear its rows from Live Signals

Riding an aircraft now adopts its layer the way a direct selection does, and
Contacts gives up a dependency the user adopts, so ending Contacts mid-session
(one of its layers off, or Contacts itself) no longer turns off the ridden
layer and ends the Cockpit. When Contacts goes off, Live Signals drops the
rows built from its snapshot instead of leaving stale distances marked
CURRENT, and the feed-off warning is no longer duplicated.

docs/CURRENT-STATE.md

@@ -6021,11 +6021,16 @@ apply to `public/` assets or built-preview serving.
   tracked: Live Flights for a civilian, Military Flights for a military aircraft
   (the tracked info's `layerId`; `cockpitEntryAllowed` in
   `src/contextModePolicy.js`). Contacts is not required, and the other aircraft
-  layer, Live AIS Vessels and every other layer may be turned on or off before or
-  during a session. A Context mode change still in flight blocks entry until it
-  settles. Turning off the layer the view rides ends it. The visible Cockpit
-  actions, the `C` shortcut and voice use the same gate; voice entry still opens
-  Contacts first, as its layer-targeted entry navigates through Contacts.
+  layer, Live AIS Vessels and every other layer may be turned on or off before
+  or during a session. A Context mode change still in flight blocks entry until
+  it settles. Turning off the layer the view rides ends it. Riding an aircraft
+  while Contacts is on adopts its layer as the user's own, as a direct selection
+  does (`adoptLayerVisibility`), so Contacts ending, by its own switch or one of
+  its layers going off, restores the pre-Contacts layers but keeps the ridden
+  one and the view; Live Signals then drops the rows Contacts built and shows
+  `CONTEXT STANDBY`. The visible Cockpit actions, the `C` shortcut and voice use
+  the same gate; voice entry still opens Contacts first, as its layer-targeted
+  entry navigates through Contacts.
 - **Aircraft cockpit view:** selecting a commercial or military aircraft reveals a `COCKPIT` action (`C`) once that aircraft's own layer is on; Contacts is not required. The action shows in Contacts (`#cockpit-entry`) and under the Intel HUD's bottom-right readout (`#cockpit-entry-readout`, with the HUD on, in its Tactical and Cyber layouts), so entry needs no Contacts panel. Turning off the ridden aircraft's layer ends the view (the layer clears its tracking). When an air feed the surrounding picture uses is off, the Cockpit says so instead of blocking: Live Signals leads with `MILITARY FEED OFF · PARTIAL PICTURE` or `FLIGHTS FEED OFF · PARTIAL PICTURE`, and the Contact card shows that line in place of its inputs status, so a partial picture is never presented as complete. `control_cockpit` refuses entry with `entryBlockedReason` `contacts-starting` (a Context change in flight), `subject-layer-off` (the aircraft's layer, or with none tracked any aircraft layer, is off) or `no-tracked-aircraft`. Cockpit mode temporarily releases Cesium's orbit-follow transform and drives a first-person camera from the tracked aircraft's existing smoothed display position and course. Its concave helmet-visor HUD shows callsign, UTC time, coordinates, curved roll/pitch guides, and a seven-division heading tape. Ambient commercial and military AIR contacts use a Cockpit near/far band selected by the shared Display 3D mode: Proximity admits at 150 km and retains to 185 km; All admits at 400 km and retains to 450 km. The shared 3D toggle now applies in Cockpit: Off keeps in-range contacts as rotating 2D aircraft silhouettes, while On lets a ready admitted glTF take over without a drawing gap. The Cockpit model cap remains 60 and can only lower the map budget; in-range contacts that are capped or still loading remain 2D silhouettes instead of degrading to out-of-range dots. Contacts outside the selected band use small rotation-free cyan-white pips for civilian aircraft and amber pips for military. The pilot's own airframe is not drawn in first person, and exiting clears the Cockpit band and restores normal map silhouettes/models. The normal left accordion remains available for Layers and Authoring and keeps the same 26vh HUD-aligned anchor used in map mode, independent of whether the bottom-left Contact card is expanded or collapsed; the right-rail CCTV and Context chooser are hidden to avoid duplicating or overlapping the cockpit presentation. When the intelligence HUD is enabled, its classification, scene summary, collection/orbit metadata, coordinates, and imaging-status text remain visible as reduced peripheral cockpit telemetry; the optical center and flight instruments stay clear, and turning the HUD off still hides it. Ground speed, exact heading, and rendered altitude form one compact lower-center instrument cluster, keeping the horizon and peripheral view open. A second live altitude tape hugs the inside-right visor rim: its rail and nine moving ticks are derived from the same responsive keyhole radius, remain 20 px inside the circular edge even on wide displays, fade deeply at both vertical ends, and move continuously behind a fixed current-altitude pointer; its interval tightens automatically near the surface and it is suppressed on narrow screens. Cockpit mode also has a weather-backed transparent volumetric-cloud pass derived from the supplied FBM/domain-warped R&D shader. It renders at no more than 520×320, uses 24 ray steps/three FBM octaves at 12 FPS, is clipped to the visor, fails clear when Open-Meteo is unavailable, and stops its animation completely on cockpit exit. It does not restore the prior CPU weather canvases, precipitation, scene fog, or any map-mode effect. When Contacts is active for the tracked aircraft, the compact `CONTACT` rail adds the 250 km subject window, four cohort counts, nearest observed/mapped example with relative bearing and distance, freshness, explicit uncertainty, and Previous and Next controls plus its own collapse control. The mirrored right rail is a three-page **cockpit briefing carousel**: source-backed live signals, location-matched regional headlines, and physical-region/current-weather context from bundled Natural Earth polygons and Open-Meteo. It is manual-first: Previous, Next, and direct page controls are always available, and the visible `CYCLE OFF` / `CYCLE ON` control starts or stops the nine-second page cycle. The cycle pauses on hover or keyboard focus and stops while collapsed, hidden, or outside cockpit mode; live signal data continues refreshing either way. Empty news matches and unavailable news use compact text states rather than reserving an empty media frame; partial local data remains explicit. Article links open their original publisher, and no headline is treated as verified risk intelligence. On desktop both cockpit rails use the same width and share a bottom-aligned safe baseline in opposite corners above the peripheral MGRS/GSD/time telemetry, leavinLine truncated
 - **Cockpit left-panel clearance:** the Cockpit Contact card and peripheral HUD participate in the adaptive left accordion's live obstacle measurements, including live viewport-height changes. Expanding Layers or Authoring keeps the active panel in the available upper-left corridor with internal scrolling; it does not cover the Contact card, lower Cockpit controls, or Cesium credit line. Outside Cockpit the hidden card does not alter the normal corridor.
 - **Cockpit Context scope:** the 250 km radius applies to the air/sea proximity cohorts. Installation counts come only from the currently loaded viewport and are labeled `CURRENT VIEWPORT ONLY` in the cockpit as well as the normal Context panel; neither surface presents them as a complete 250 km installation survey.