feat(audiobookshelf): Implement shared element transitions and improve MiniPlayer UI

This commit introduces `SharedTransitionLayout` to provide a seamless visual transition for audiobook covers between the MiniPlayer and the full Audiobookshelf Player screen. It also refactors the MiniPlayer with a modern design, including swipe-to-dismiss functionality and dynamic background coloring.

### Key Changes:

*   **`MainNavigation.kt`**:
    *   Wrapped the root `NavHost` and `MiniPlayer` in a `SharedTransitionLayout` to enable shared element transitions.
    *   Updated the `audiobookshelf/player/` route and `MiniPlayer` call sites to pass the required `AnimatedVisibilityScope`.

*   **`MiniPlayer.kt`**:
    *   **Shared Element**: Added `sharedElement` modifier to the book cover image for smooth transitions.
    *   **UI Redesign**: Replaced the linear progress bar with a dynamic "fill" effect where the background color (derived from the cover) expands behind the content based on playback progress.
    *   **Interactions**: Implemented `SwipeToDismissBox` to allow users to close the mini player by swiping.
    *   **Visuals**: Switched the cover shape to `CircleShape`, added a `basicMarquee` effect to the title when playing, and increased elevation/shadows for better depth.

*   **`AudiobookshelfPlayerScreen.kt`**:
    *   Updated the screen and its content components (`PortraitPlayerContent`, `LandscapePlayerContent`) to support `SharedTransitionScope`.
    *   Added the matching `sharedElement` modifier to the cover art in both portrait and landscape layouts to complete the transition pair with the MiniPlayer.

*   **Formatting**:
    *   Performed minor indentation and code style adjustments across modified files.

Author: MakD