- Add fetch() API with json(), text(), arrayBuffer() methods
- Add atob()/btoa() global Base64 functions
- Add TextEncoder/TextDecoder classes for UTF-8 encoding
- Add URL/URLSearchParams classes for URL parsing
- Update documentation with polyfill usage examples
- All polyfills work within sandbox security model
- Add http.put(), http.delete(), http.patch() shortcut methods
- Add persistent cookie jar per extension
- Add http.clearCookies() to clear session
- Fix User-Agent header respect (no longer overwritten)
- Return multi-value headers as arrays (Set-Cookie support)
- Auto-stringify objects in POST/PUT/PATCH body
- Add response.ok and response.status properties
- Update documentation with YouTube Music example
- Add extension manager, manifest, runtime, providers, settings
- Add extension provider and UI pages (extensions, detail, priority)
- Add download service picker widget
- Add metadata provider priority page
- Add source field to Track model for extension tracking
- Add skipBuiltInFallback manifest option to skip built-in providers
- Update download queue to use source extension first
- Add extension upgrade support without data loss
zarzet