refactor: modernize Cast discovery and app activation

TODO.md

@@ -19,4 +19,5 @@
         - Open Stream routes YouTube videos and explicit barelystarted.miruro.tv episode links; live Miruro video/audio and VTT seek checks passed, with shared validated source metadata and unchanged Tubular source/progress contracts; CLI handoff emitted v2 playback/end facts, but its GUI-state checker timed out without snapshots; physical UI/drop/Cast verification remains unverified
 - [x] check whether we're using appropriately new apple ui APIs / SDKs for the project.
     - we should strive to use modern and idiomatic SDKs and APIs including SwiftUI among others
-    - audited SDK 27.0 / Swift 6.4 with a consistent macOS 15 minimum; SwiftUI already owns the UI, and native bridges retain required behavior. Scoped migration candidates: Network-framework Cast discovery and cooperative app activation; Observation and native Liquid Glass remain elective. Forced Swift/native builds, Mach-O SDK/minimum checks, CLI and dylib-load smoke passed; findings and Apple references are in README's Apple SDK and UI API audit. No runtime/UI behavior changed; macOS 15 runtime and visual verification were not performed.
+    - audited SDK 27.0 / Swift 6.4 with the macOS 15 minimum retained; migrated Cast discovery to NWBrowser and production activation to activate(). Real Bonjour identity/name/update/order/deduplication/removal/restart and routable-endpoint checks, loopback Cast transitions, focused startup-error alerts and a cooperating-launcher production smoke for cold start/CLI reuse/document handoff/keyboard playback passed. The existing full CLI snapshot-harness timeout remains; macOS 15 runtime and physical-Cast verification remain unverified. Observation, glass and the existing native bridges were left unchanged.
+- [ ] fix the readme. it's currently bloated with irrelevant implementation detail and other such nonsense.