feat: add PWA manifest and service worker (#485)

- Add manifest.json with app name, theme color, display=fullscreen, and icon references
- Add sw.js with cache-first strategy for assets and network-first for API calls
- Update index.html with <link rel="manifest"> and SW registration script
- Cache key nexus-v3, precaches core assets from jsdelivr CDN
- Network-first for Gitea API and WebSocket requests

Fixes #485

index.html

@@ -19,6 +19,8 @@
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <title>The Nexus — Timmy's Sovereign Home</title>
+<link rel="manifest" href="/manifest.json">
+<meta name="theme-color" content="#050510">
 <link rel="preconnect" href="https://fonts.googleapis.com">
 <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
 <link href="https://fonts.googleapis.com/css2?family=JetBrains+Mono:wght@300;400;500;600;700&family=Orbitron:wght@400;500;600;700;800;900&display=swap" rel="stylesheet">
@@ -172,6 +174,12 @@
 
 <script type="module" src="./app.js"></script>
 
+<script>
+if ('serviceWorker' in navigator) {
+  navigator.serviceWorker.register('/sw.js').catch(() => {});
+}
+</script>
+
 <!-- Live Refresh: polls Gitea for new commits on main, reloads when SHA changes -->
 <div id="live-refresh-banner" style="
   display:none; position:fixed; top:0; left:0; right:0; z-index:9999;

manifest.json

@@ -0,0 +1,20 @@
+{
+  "name": "Timmy's Nexus",
+  "short_name": "Nexus",
+  "start_url": "/",
+  "display": "fullscreen",
+  "background_color": "#050510",
+  "theme_color": "#050510",
+  "icons": [
+    {
+      "src": "icons/t-logo-192.png",
+      "sizes": "192x192",
+      "type": "image/png"
+    },
+    {
+      "src": "icons/t-logo-512.png",
+      "sizes": "512x512",
+      "type": "image/png"
+    }
+  ]
+}

sw.js

@@ -0,0 +1,95 @@
+// The Nexus — Service Worker
+// Cache-first for assets, network-first for API calls
+
+const CACHE_NAME = 'nexus-v3';
+const ASSET_CACHE = 'nexus-assets-v3';
+
+const CORE_ASSETS = [
+  '/',
+  '/index.html',
+  '/app.js',
+  '/style.css',
+  '/manifest.json',
+  'https://cdn.jsdelivr.net/npm/three@0.183.0/build/three.module.js',
+  'https://cdn.jsdelivr.net/npm/three@0.183.0/examples/jsm/controls/OrbitControls.js',
+  'https://cdn.jsdelivr.net/npm/three@0.183.0/examples/jsm/postprocessing/EffectComposer.js',
+  'https://cdn.jsdelivr.net/npm/three@0.183.0/examples/jsm/postprocessing/RenderPass.js',
+  'https://cdn.jsdelivr.net/npm/three@0.183.0/examples/jsm/postprocessing/UnrealBloomPass.js',
+  'https://cdn.jsdelivr.net/npm/three@0.183.0/examples/jsm/postprocessing/ShaderPass.js',
+  'https://cdn.jsdelivr.net/npm/three@0.183.0/examples/jsm/shaders/CopyShader.js',
+  'https://cdn.jsdelivr.net/npm/three@0.183.0/examples/jsm/shaders/LuminosityHighPassShader.js',
+];
+
+// Install: precache core assets
+self.addEventListener('install', (event) => {
+  event.waitUntil(
+    caches.open(ASSET_CACHE).then((cache) => cache.addAll(CORE_ASSETS))
+      .then(() => self.skipWaiting())
+  );
+});
+
+// Activate: clean up old caches
+self.addEventListener('activate', (event) => {
+  event.waitUntil(
+    caches.keys().then((keys) =>
+      Promise.all(
+        keys
+          .filter((key) => key !== CACHE_NAME && key !== ASSET_CACHE)
+          .map((key) => caches.delete(key))
+      )
+    ).then(() => self.clients.claim())
+  );
+});
+
+self.addEventListener('fetch', (event) => {
+  const { request } = event;
+  const url = new URL(request.url);
+
+  // Network-first for API calls (Gitea / WebSocket upgrades / portals.json live data)
+  if (
+    url.pathname.startsWith('/api/') ||
+    url.hostname.includes('143.198.27.163') ||
+    request.headers.get('Upgrade') === 'websocket'
+  ) {
+    event.respondWith(networkFirst(request));
+    return;
+  }
+
+  // Cache-first for everything else (local assets + CDN)
+  event.respondWith(cacheFirst(request));
+});
+
+async function cacheFirst(request) {
+  const cached = await caches.match(request);
+  if (cached) return cached;
+
+  try {
+    const response = await fetch(request);
+    if (response.ok) {
+      const cache = await caches.open(ASSET_CACHE);
+      cache.put(request, response.clone());
+    }
+    return response;
+  } catch {
+    // Offline and not cached — return a minimal fallback for navigation
+    if (request.mode === 'navigate') {
+      const fallback = await caches.match('/index.html');
+      if (fallback) return fallback;
+    }
+    return new Response('Offline', { status: 503, statusText: 'Service Unavailable' });
+  }
+}
+
+async function networkFirst(request) {
+  try {
+    const response = await fetch(request);
+    if (response.ok) {
+      const cache = await caches.open(CACHE_NAME);
+      cache.put(request, response.clone());
+    }
+    return response;
+  } catch {
+    const cached = await caches.match(request);
+    return cached || new Response('Offline', { status: 503, statusText: 'Service Unavailable' });
+  }
+}