Add Web Push, guided start screen, SVG icons, chunked uploads, rename

- Web Push (VAPID + RFC 8291, pure Rust): permission/question/finished
  notifications while no app window is visible; settings with test button
- Guided new-session flow: task, craft target (website/app/game/old
  software/fresh), clean room or deep, description, model, folder
  (new, existing or cloned git repository); originals upload to original/
- Craft phase bar (craft_phase tool) for study/specify/build/check/ready
- Chunked uploads (8 MB) up to server.max_upload_mb (default 500 MB)
- All UI glyphs and emojis replaced by themeable SVG icons
- Rename dialog with manual name or model-generated suggestion

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

web/src/push.ts

@@ -0,0 +1,53 @@
+import { get, post } from "./api";
+
+function b64ToBytes(b64: string): Uint8Array<ArrayBuffer> {
+  const s = atob(b64.replace(/-/g, "+").replace(/_/g, "/") + "===".slice((b64.length + 3) % 4));
+  const out = new Uint8Array(new ArrayBuffer(s.length));
+  for (let i = 0; i < s.length; i++) out[i] = s.charCodeAt(i);
+  return out;
+}
+
+export const pushSupported = () => "serviceWorker" in navigator && "PushManager" in window && "Notification" in window;
+
+/** Current push subscription of this device (null if none). */
+export async function currentSubscription(): Promise<PushSubscription | null> {
+  if (!pushSupported()) return null;
+  const reg = await navigator.serviceWorker.ready;
+  return reg.pushManager.getSubscription();
+}
+
+/** Ask for permission, subscribe this device and register it with the server. */
+export async function enablePush(): Promise<void> {
+  if (!pushSupported()) throw new Error("Push is not supported by this browser (on iOS: install the app to the home screen first).");
+  const perm = await Notification.requestPermission();
+  if (perm !== "granted") throw new Error("Notifications were not allowed.");
+  const reg = await navigator.serviceWorker.ready;
+  const { key } = await get<{ key: string }>("/push/key");
+  let sub = await reg.pushManager.getSubscription();
+  // A subscription for another server key must be replaced.
+  if (sub && sub.options.applicationServerKey) {
+    const cur = new Uint8Array(sub.options.applicationServerKey);
+    const want = b64ToBytes(key);
+    if (cur.length !== want.length || cur.some((b, i) => b !== want[i])) {
+      await sub.unsubscribe();
+      sub = null;
+    }
+  }
+  if (!sub) sub = await reg.pushManager.subscribe({ userVisibleOnly: true, applicationServerKey: b64ToBytes(key) });
+  await post("/push/subscribe", sub.toJSON());
+  localStorage.setItem("codecraft.push", "1");
+}
+
+export async function disablePush(): Promise<void> {
+  const sub = await currentSubscription();
+  if (sub) {
+    await fetch("/api/push/subscribe", { method: "DELETE", credentials: "same-origin", headers: { "Content-Type": "application/json" }, body: JSON.stringify({ endpoint: sub.endpoint }) });
+    await sub.unsubscribe();
+  }
+  localStorage.removeItem("codecraft.push");
+}
+
+export async function testPush(): Promise<number> {
+  const r = await post<{ sent: number }>("/push/test", {});
+  return r.sent;
+}