Stand-in import of elffuss/code

One parentless commit with only the files that the open seed tasks touch and the modules they import.
The full squashed import (SPEC 8.6) is a later step: this tree is not the cutoff tree.

T2T-StandIn-Source-Commit: 43f95b7333efe73aeaebf806023f17bffea27aba

web/js/model-cache.js

@@ -0,0 +1,51 @@
+// Arranque de la caché de modelos: (1) pide almacenamiento PERSISTENTE para que
+// el navegador no desaloje los pesos cacheados, y (2) registra el service worker
+// (sw.js) y espera a que CONTROLE la página antes de descargar nada — así hasta
+// la primera descarga queda cacheada. Idempotente y a prueba de fallos.
+let started = null;
+
+export function ensureModelCache() {
+  if (started) return started;
+  started = (async () => {
+    try {
+      if (navigator.storage && navigator.storage.persist) {
+        const persisted = navigator.storage.persisted ? await navigator.storage.persisted() : false;
+        const ok = persisted || await navigator.storage.persist();
+        console.log('[elffuss] almacenamiento persistente:', ok);
+      }
+    } catch { /* no soportado */ }
+
+    if (!('serviceWorker' in navigator)) return false;
+    try {
+      await navigator.serviceWorker.register('sw.js');
+      await navigator.serviceWorker.ready;
+      if (!navigator.serviceWorker.controller) {
+        await new Promise(res => {
+          const t = setTimeout(res, 1500);
+          navigator.serviceWorker.addEventListener('controllerchange', () => { clearTimeout(t); res(); }, { once: true });
+        });
+      }
+      console.log('[elffuss] caché de modelos activa (service worker)');
+      return true;
+    } catch (e) {
+      console.warn('[elffuss] service worker no disponible:', e.message);
+      return false;
+    }
+  })();
+  return started;
+}
+
+// Espacio ocupado por la caché (para mostrarlo en Ajustes).
+export async function cacheEstimate() {
+  try {
+    const e = await navigator.storage.estimate();
+    return { usage: e.usage || 0, quota: e.quota || 0, persisted: navigator.storage.persisted ? await navigator.storage.persisted() : false };
+  } catch { return { usage: 0, quota: 0, persisted: false }; }
+}
+
+// Vaciar la caché de modelos (botón en Ajustes).
+export async function clearModelCache() {
+  if (navigator.serviceWorker && navigator.serviceWorker.controller)
+    navigator.serviceWorker.controller.postMessage('clear-models');
+  try { await caches.delete('elffuss-models-v1'); } catch { /* */ }
+}