fix(android): back focus lost after tabbing out — re-assert overlay back callbacks on resume

With NowPlaying (or an ABS player) open, backgrounding and resuming the app made the next back
press pop the NavHost invisibly to Home before dismissing the overlay. Returning from the
background re-registers the NavController's own OnBackPressedCallback on top of the dispatcher,
stealing back-priority from the overlays.

AppNavigation now bumps a resumeTick on Lifecycle.Event.ON_RESUME and keys every overlay
DisposableEffect (NowPlaying, ABS player, ABS item, Erkunden overlay) on resumeTick +
currentBackEntry, so each overlay re-adds its callback above the NavController after a resume or
navigation. Needs on-device verification.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CLAUDE.md

@@ -132,6 +132,12 @@ Backend runs in Docker (see `docker-compose.yml`); on the deploy host it lives a
   its close action upward via `onOverlayBackChange`, and `AppNavigation` registers a **root-level**
   `OnBackPressedCallback` for it (the same mechanism the NowPlaying overlay always used successfully).
   Real nav routes (`album/{id}`, `artist/{id}`) are unaffected — `popBackStack()` is correct there.
+- **Re-assert root-level back callbacks on `ON_RESUME`, not just on navigation.** Returning from the
+  background re-registers the NavController's own `OnBackPressedCallback` on **top** of the dispatcher,
+  which steals back-priority from the NowPlaying/ABS/Erkunden overlays — back then pops the NavHost
+  (invisibly, to Home) before dismissing the visible overlay. Fix in `AppNavigation`: a `resumeTick`
+  (`LifecycleEventEffect(ON_RESUME)`) plus `currentBackEntry` are keys on every overlay's
+  `DisposableEffect`, so each re-adds (bumps itself above the NavController) after a resume or a nav.
 - **Overlay state belongs in the ViewModel, not `remember`.** Anything an overlay shows (e.g. the
   artist's "all albums" section) is destroyed when the user drills into an album, because the overlay
   leaves composition. `rememberSaveable` does **not** save you — it only survives for real nav