refactor(military): Cesium rendering behind a renderer interface

Task 11a. The military flights logic no longer imports Cesium: it draws
through the shared aircraft renderer (src/layers/aircraft/render/cesium.js)
with the military's parameters in src/layers/military/render/cesium.js
(sprite-order slot 'military', jet.glb's 180° nose offset), registered for
'cesium' in the renderer registry and created at init(viewer, {engine}).
The same pure move as flights in 10a:

- Fleet: the BillboardCollection and its sprite-order slot (enable keeps
  restoreSpriteOrder, as before); sprites stay Billboard handles.
- Models: fleet/tracked/preload glTF loads (asynchronous:false, MIX tint at
  MODEL_COLOR_BLEND_AMOUNT, IR boost as `unlit` → the UNLIT CustomShader),
  the model collection, setPose. The per-class specs keep their own nose
  offset: setPose takes an optional offsetDeg (default the layer's), on
  both aircraft renderers (same arithmetic, test added).
- Tracked: the ENU billboard Entity with its position/colour/rotation
  callbacks (#FFD166, transparent amber once the model owns the visual),
  viewFrom, followed through viewer.trackedEntity + the one exact tracked
  frame; refocusTrackedById through follow.refocus.
- Trail: the entity trail and the floored live head segment.
- View: camera/scene reads, frame number, frustum and horizon tests,
  render requests, frame events.
- Clicks and Escape go through the engine's selection dispatcher (the
  ScreenSpaceEventHandler and keydown listener are gone); the cross-layer
  untrack watches the renderer's follow. Same rules: cockpit clicks are
  inert, the tracked visual/model is a no-op, another layer's pick is not
  empty space, an unowned pick is.
- Colours are engine-neutral Rgba (MIL_ICON_COLOR #FFB800,
  TRACKED_ICON_COLOR #FFD166, AMBER_TRANSPARENT), NearFarScalar →
  nearFarScale; Cesium math → src/geo.
- check-import-directions: src/layers/military/ joins the rendered layers
  (cesium only in render/cesium*.js).
- The military registry and the flights' duplicate suppression are
  untouched.

Source-text tests updated with the moved code, same meaning:
- militaryAwareness.test: military's hasContact guard reads fleet.visible().
- trackingClickGesture.test: the military gesture rules are the
  dispatcher's (selection gesture before select, click classifier before
  the empty-space clear), military answers the empty click with a
  user-origin clear — the same assertion flights already had.
- ownership.test: the services fixture names selection and renderer; the
  app-composed services build the layer's Cesium renderer.
- renderers.test: flights and military have extracted Cesium renderers.

New tests: the military logic over a plain-data renderer and a fake engine
(amber fleet, click-select, #FFD166 tracked glyph, no-op on the tracked
visual, empty-click and Escape release, the keyboard left on destroy); the
plain-data renderer moved to src/testSupport for both aircraft layers;
setPose with a per-model offset.

W1 replay vs 7c7422e2 (the 10a reference run): every layer's counts, known
objects, screen points, tracking pose after 2 s, requests and the
city/global/orbit shots (sha256) identical. qa-military-names (it checks
the installations layer): the same verdict as 7c7422e2 (the zoom-markers
assertion fails on both). Main chunk 2,890,763 B (−2.9 KB).

scripts/package-boundaries.json

@@ -935,6 +935,7 @@
       "src/layers/military/records.js",
       "src/layers/military/recordPolicy.js",
       "src/layers/military/snapshotRenderer.js",
+      "src/layers/shared/color.js",
       "src/data/inputOwnership.js",
       "src/data/modelEligibility.js",
       "src/geo/index.js",
@@ -2591,6 +2592,7 @@
       "src/app/layers/renderers.js",
       "src/layers/aircraft/render/cesium.js",
       "src/layers/flights/render/cesium.js",
+      "src/layers/military/render/cesium.js",
       "src/data/selectionDispatcher.js",
       "src/layers/shared/color.js",
       "src/layers/aircraft/render/navara.js",
@@ -3169,7 +3171,8 @@
       "src/layers/aircraft/render/cesium.js",
       "src/data/selectionDispatcher.js",
       "src/layers/shared/color.js",
-      "src/layers/flights/render/cesium.js"
+      "src/layers/flights/render/cesium.js",
+      "src/layers/military/render/cesium.js"
     ],
     "external": [
       "hls.js",