feat: launch readiness — PWA, API hardening, memory leak fixes, sticker removal

- Add PWA infrastructure: vite-plugin-pwa, manifest, service worker,
  SW update prompt component, placeholder icons, Apple meta tags
- Harden API client: 401 auto-logout, AbortController timeouts
  (30s standard, 120s uploads), onUnauthorized callback
- Fix memory leaks: clear voice user status on leave, clean up all
  Maps (channelToSpaceMap, permissions, etc.) on removeSpace
- Upgrade error boundary to Aether Drift design with Try Again button,
  collapsible stack trace, and componentDidCatch logging
- Configure desktop icon paths in electron-builder.yml
- Remove sticker feature (server routes, schema, types, UI components)
- Fix Docker build: use **/node_modules in .dockerignore to prevent
  COPY from clobbering pnpm-installed workspace dependencies
- Add vite-env.d.ts declarations for noise suppressor wasm imports
- Exclude test files from tsc build via tsconfig

packages/web/vite.config.ts

@@ -1,10 +1,35 @@
 /// <reference types="vitest" />
 import { defineConfig } from 'vite';
 import react from '@vitejs/plugin-react';
+import { VitePWA } from 'vite-plugin-pwa';
 import path from 'path';
 
 export default defineConfig({
-  plugins: [react()],
+  plugins: [
+    react(),
+    VitePWA({
+      registerType: 'prompt',
+      includeAssets: ['icons/favicon-32.png', 'icons/favicon-16.png', 'icons/apple-touch-icon.png'],
+      manifest: {
+        name: 'Backspace',
+        short_name: 'Backspace',
+        description: 'Self-hosted chat platform',
+        display: 'standalone',
+        start_url: '/',
+        theme_color: '#0b0b10',
+        background_color: '#0b0b10',
+        icons: [
+          { src: '/icons/icon-192.png', sizes: '192x192', type: 'image/png' },
+          { src: '/icons/icon-512.png', sizes: '512x512', type: 'image/png' },
+          { src: '/icons/icon-maskable-512.png', sizes: '512x512', type: 'image/png', purpose: 'maskable' },
+        ],
+      },
+      workbox: {
+        navigateFallback: '/index.html',
+        navigateFallbackDenylist: [/^\/api/, /^\/ws/, /^\/uploads/],
+      },
+    }),
+  ],
   test: {
     globals: true,
     environment: 'jsdom',