Retire stale WebUI service workers on startup

[mirek190]

Summary

Fix the embedded Native WebUI remaining stuck on a previously installed application when audio.cpp reuses the same local origin, commonly http://127.0.0.1:8080.
In short - If you had other webpage on http://127.0.0.1 and port 8080 loaded before the cache was not released and you could nor see Audio.cpp Studio on working server until you do not clean cache manually.

Root cause

A prior llama.cpp WebUI registered a root-scoped /sw.js Workbox service worker. That worker continued serving its cached application shell before requests reached audiocpp_server, so normal Edge sessions displayed the old UI while InPrivate sessions correctly displayed Native Studio. Ordinary HTTP cache headers alone cannot retire a service worker that intercepts the navigation first.

Changes

• Serve no-store/no-cache headers and Clear-Site-Data: cache for the embedded UI shell.
• Provide retirement workers at /sw.js and /service-worker.js when the UI is enabled.
• The retirement worker replaces a stale registration, clears Cache Storage, unregisters itself, and reloads controlled windows.
• Native Studio also unregisters any remaining workers and clears Cache Storage during startup.
• Deliberately preserve localStorage and IndexedDB so saved voices, model-folder selection, language, and UI preferences survive.
• Regenerate the embedded SvelteKit output.

Validation

• npm run check: 0 errors and 0 warnings.
• npm run build: successful static Native Studio build.
• Windows CUDA Release audiocpp_server build: successful.
• Verified / returns Cache-Control: no-store, no-cache, must-revalidate, max-age=0 and Clear-Site-Data: cache.
• Verified /sw.js returns the no-store retirement worker with root service-worker scope.
• Browser regression: a synthetic legacy Cache Storage entry was removed after reload while a localStorage preference remained intact; no service-worker registrations remained.
• Reproduced with a normal Microsoft Edge profile containing llama.cpp's old /sw.js and Workbox cache; reopening 127.0.0.1:8080 automatically recovered to audio.cpp · Native Studio. InPrivate mode was not required.

[0xShug0]

Merged! Thanks!