feat: add standalone tasks PWA build

Adds a standalone tasks PWA at tasks.${domain}, built from the
existing src/modules/tasks plugin (Nostr calendar events, kind
31922/31925). Same standalone pattern as the other modules:
- tasks.html entry, vite.tasks.config.ts (outDir: dist-tasks,
  manifest id: tasks-app, theme: indigo #4338ca — Ajna chakra)
- src/tasks-app/{main.ts, app.ts, app.config.ts, App.vue} bootstraps
  base + tasks only, with acceptTokenFromUrl for shared auth from hub
- npm run dev:tasks / build:tasks / preview:tasks
- main app SW denylist extended with /tasks/

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

vite.config.ts

@@ -25,7 +25,7 @@ export default defineConfig(({ mode }) => ({
           '**/*.{js,css,html,ico,png,svg}'
         ],
         // Don't intercept standalone app paths — they have their own service workers
-        navigateFallbackDenylist: [/^\/sortir\//, /^\/castle\//],
+        navigateFallbackDenylist: [/^\/sortir\//, /^\/castle\//, /^\/tasks\//],
       },
       includeAssets: [
         'favicon.ico',