Add a Navara HD renderer choice, release a parked engine after three minutes, and cut Navara's memory

Navara now draws at CSS pixels without MSAA, like Cesium; Navara HD keeps the device pixel ratio and MSAA 4. Only one Navara variant is ever kept. A parked engine is released after three minutes and its WebGL context is lost. Three leaks that kept a released Navara alive are fixed, the canvas context drops its unused antialias buffer, cloud shadows use two 256 px cascades, and the tile cache is budgeted from the screen buffers.

scripts/qa-strict-harness.mjs

@@ -29,6 +29,8 @@ import {
 import { createMissLoader, tileCacheFile } from './qa/tileCache.mjs';
 
 export const ENGINES = Object.freeze(['cesium', 'navara']);
+/** What the Globe Engine picker offers: the engines and Navara HD. */
+const CHOICES = Object.freeze([...ENGINES, 'navara-hd']);
 /** Local ports that belong to the user's own servers: never a QA preview. */
 export const RESERVED_PORTS = Object.freeze([
   '',
@@ -406,7 +408,7 @@ export async function pickEngine(
   kind,
   { settle = true, afterInput = null } = {},
 ) {
-  assert.ok(ENGINES.includes(kind), kind);
+  assert.ok(CHOICES.includes(kind), kind);
   const expanded = () =>
     page.$eval(
       '#control-panel-toggle',
@@ -430,6 +432,21 @@ export async function pickEngine(
   });
   const from = await page.$eval('#globe-engine', (el) => el.value);
   assert.notEqual(from, kind, `the picker already shows ${kind}`);
+  // The key typed below is `kind`'s first letter: it selects the next option
+  // starting with it (after `from` when `from` starts with it too). Each key
+  // is a change that starts a switch, so `kind` must be one key away
+  // (Cesium → Navara HD goes through Navara).
+  const values = await page.$$eval('#globe-engine option', (options) =>
+    options.map((option) => option.value),
+  );
+  const matches = values.filter((value) => value[0] === kind[0]);
+  assert.equal(
+    from[0] === kind[0]
+      ? matches[(matches.indexOf(from) + 1) % matches.length]
+      : matches[0],
+    kind,
+    `${kind} is not one key away from ${from}`,
+  );
   // Where a pointer can reach the picker: the label's own text (focuses the
   // select without opening its menu), else the select itself.
   const target = await page.$eval('#globe-engine', (el) => {
@@ -537,7 +554,9 @@ export async function pickEngine(
 export async function waitForEngine(page, kind, { timeout = 120000 } = {}) {
   await page.waitForFunction(
     (expected) =>
-      window.__godsEyeView?.engine?.kind === expected &&
+      // Navara HD runs the Navara engine.
+      window.__godsEyeView?.engine?.kind ===
+        (expected === 'cesium' ? 'cesium' : 'navara') &&
       document.querySelector('#globe-engine')?.value === expected &&
       !document.querySelector('#globe-engine')?.disabled &&
       !document.querySelector('.engine-switch-frame') &&