Initial WhatToDo app

Self-hosted personal task list: FastAPI + SQLite in Docker, mobile-friendly
PWA frontend, deadlines, priorities, categories, tags, notes, checklists,
recurring tasks, single-password login, and JSON export/import.

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

app/static/sw.js

@@ -0,0 +1,35 @@
+// Network-first service worker: always fresh when online, app shell still opens offline.
+const CACHE = 'whattodo-v1';
+const SHELL = [
+  './', 'index.html', 'style.css', 'app.js', 'manifest.webmanifest',
+  'icons/icon.svg', 'icons/icon-192.png', 'icons/icon-512.png',
+];
+
+self.addEventListener('install', (event) => {
+  event.waitUntil(caches.open(CACHE).then((c) => c.addAll(SHELL)).then(() => self.skipWaiting()));
+});
+
+self.addEventListener('activate', (event) => {
+  event.waitUntil(
+    caches.keys()
+      .then((keys) => Promise.all(keys.filter((k) => k !== CACHE).map((k) => caches.delete(k))))
+      .then(() => self.clients.claim()),
+  );
+});
+
+self.addEventListener('fetch', (event) => {
+  const req = event.request;
+  const url = new URL(req.url);
+  if (req.method !== 'GET' || url.origin !== self.location.origin || url.pathname.includes('/api/')) return;
+  event.respondWith(
+    fetch(req)
+      .then((res) => {
+        if (res.ok) {
+          const copy = res.clone();
+          caches.open(CACHE).then((c) => c.put(req, copy));
+        }
+        return res;
+      })
+      .catch(() => caches.match(req).then((hit) => hit || caches.match('index.html'))),
+  );
+});