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-session.mjs

@@ -103,10 +103,19 @@ export async function installSessionFixtures(
   );
 }
 
-/** Open the app on `engine` with the session hash and wait until it runs. */
-export async function openApp(page, origin, engine, hash = SESSION_HASH) {
+/**
+ * Open the app on `engine` with the session hash (and `search`, more query
+ * parameters such as `&parkedMs=3000`) and wait until it runs.
+ */
+export async function openApp(
+  page,
+  origin,
+  engine,
+  hash = SESSION_HASH,
+  search = '',
+) {
   const url = new URL(origin);
-  url.search = `?engine=${engine}&welcome=0`;
+  url.search = `?engine=${engine}&welcome=0${search}`;
   url.hash = hash;
   await page.goto(url.href, { waitUntil: 'domcontentloaded' });
   await waitForEngine(page, engine);