docs(eink): the two e-ink builds in the docs and the site's sim

Docs: the E-ink section describes the landscape and portrait builds, what
the tall screens add, and the settings, with three screenshots; the e-ink
build flags; the release file names. Sim: each orientation gets its own
factory, so a page can load both, and simEinkScale 0 leaves the canvas'
CSS size to the page. CI builds both into solo-sim-wasm.zip (wasm/eink/).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

variants/sim/web/index.html

@@ -215,7 +215,7 @@
       }
     }
 
-    const SimFactory = window.MeshCoreSimEink || window.MeshCoreSim;
+    const SimFactory = window.MeshCoreSimEinkLandscape || window.MeshCoreSimEinkPortrait || window.MeshCoreSim;
     if (typeof SimFactory !== 'function') {
       statusEl.textContent = 'error: build/meshcore_sim.js missing or failed to load -- run variants/sim/build_wasm.sh first.';
     } else {

variants/sim/web/mesh.html

@@ -238,7 +238,7 @@
   </script>
   <script>
     const logEl = document.getElementById('log');
-    const FactoryA = (opts) => (A_BUILD ? MeshCoreSimEink : MeshCoreSim)(opts);
+    const FactoryA = (opts) => (window.MeshCoreSimEinkLandscape || window.MeshCoreSimEinkPortrait || MeshCoreSim)(opts);
     function log(msg) {
       const line = document.createElement('div');
       line.textContent = '[' + new Date().toISOString().substr(11, 12) + '] ' + msg;